It is today sadly forgotten, that NATO was created not with one, but with two objectives. The second objective of NATO was to retain inner peace, that is, keep the peace amongst NATO's own members. When NATO was created, future peace between Germany and its neighbors was yet far from secured, especially as seen from the perspective of Germany's neighbors at the time, not least France. Thus, the saying of NATO-creator Lord Ismay included that NATO should “keep the Soviet Union out”, but also “the Germans down”, that is, to keep NATO members safe, also from themselves. NATO was never only about Russia.
Letting the USA out of NATO would imply subsuming the European part of NATO into the EU. Such a possible development can have many advantages for the countries concerned, as well as for Russia.
First of all, subsuming a “NATO-excluding-the-USA” into the EU would, as mentioned, force the Europeans (including the eastern ones) to take full responsibility for their own security. This will prevent “moral hazard” of political escalations in the hope that the USA will “save” them or spend money on them for new US bases in their location. An EU-NATO (without the USA) would have to find new ways of working with the UK as well as with, of course, Russia.
Second, there is sometimes a profound need for measures outside Europe, where security and civilian efforts need to be thoroughly coordinated.
It is today sadly forgotten, that NATO was created not with one, but with two objectives. The second objective of NATO was to retain inner peace, that is, keep the peace amongst NATO's own members. When NATO was created, future peace between Germany and its neighbors was yet far from secured, especially as seen from the perspective of Germany's neighbors at the time, not least France. Thus, the saying of NATO-creator Lord Ismay included that NATO should “keep the Soviet Union out”, but also “the Germans down”, that is, to keep NATO members safe, also from themselves. NATO was never only about Russia.
Today Germany is a great and constructive neighbor in Europe. But Europe sadly still sees other inner-neighbor relations, which unfortunately cannot yet be considered absolutely stable. One only needs to refer to the afterglows of the Yugoslav wars. From that perspective, it can be argued that all Balkan countries should be part of NATO — not to protect them against “Russia”, or to strengthen NATO externally for that matter, but simply to enhance the safe development of all the Balkan countries concerning one another. Bosnia-Herzegovina is especially relevant here since the country is not even fully stabilized internally yet. There are also other less warm neighbor issues, but still potential minority-heats, notably related to eastern NATO members. NATO keeps all such inner-relations from potentially flaring up, which may also be said to be in the interest of Russia, and of Russia's partner in the Balkan area, Serbia. We should note too, that the EU also has a vital and overlapping interests to co-work in this region.
The Caucasus is here another and very separate question. It is difficult to see any possible NATO enlargement in the Caucasus as stabilizing, perhaps somewhat on the contrary. And the EU is also a more distant partner in the Caucasus. Turkey is, on the other hand, a new and also interesting discussion. Some (perhaps even a kind of “choir”) have started to discuss, whether Turkey still “fits” into NATO. On the other hand, to retain peace (again, not in relations with Russia, but here Turkey-Greece and even Cyprus), there is still an argument that peace can be best served with Turkey continuing as partner in NATO (no matter which nationality of weapons Turkey should wish to buy, actually).
An important discussion can start to revolve around whether the USA still belongs to NATO. Right-sizing is not enlarging; it is a change of configuration. Such a change in configuration is possible in that the USA (and we already see increasing Atlantic fractions) could leave NATO, and let the Europeans (including East-European states) take full responsibility for their own safety (including allowing all the Balkan countries into such an EU-NATO arrangement).
Letting the USA out of NATO would imply subsuming the European part of NATO into the EU. Such a possible development can have many advantages for the countries concerned, as well as for Russia.
First of all, subsuming a “NATO-excluding-the-USA” into the EU would, as mentioned, force the Europeans (including the eastern ones) to take full responsibility for their own security. This will prevent “moral hazard” of political escalations in the hope that the USA will “save” them or spend money on them for new US bases in their location. An EU-NATO (without the USA) would have to find new ways of working with the UK as well as with, of course, Russia.
Second, there is sometimes a profound need for measures outside Europe, where security and civilian efforts need to be thoroughly coordinated. Using NATO “out-of-area” tends to be a recipe for disaster today, and the NATO-bombing creating a collapse of Libya was one such catastrophic example. Complex civilian needs during conflict basically cannot be taken care of by NATO, because NATO as an organisation (though big enough in bureaucracy) is simply not designed for civilian efforts in connection with conflict. NATO was created to deter an all-destructive war, which would probably not have left much civilian life left to "reconstruct" afterwards. The cold-war scenario was therefore so totally different from the many extremely complicated social-economical-etchnical-religious-resource-climate-poverty types of civilian-military problems, which we see around in the world of today. That is why NATO interventions automatically, because of the organization's outdated design to focus so heavily on a now defunct “all-or-nothing” type of armagedon-conflict tends to create purely military, and hence quite destructive, approaches. NATO is still so much designed as a hammer, that sadly too many problems seem to be perceived as if they had the shape of nails. As another example of the results of this, take a look at Afghanistan, where most of NATO's “military-civilian” approaches in reality tended to become too much “military-more-military” approaches.
NATO is designed as a pure military organization, an by all means, militaries are (still) designed only to destruct, not to construct. NATO simply does not have notable resources for civilian efforts to go with its military efforts. In parallel to this, we regrettably also see in the USA a very unfortunate long-term general tendency to militarize US foreign policy, sometimes at the expense of resources and focus for civilian US foreign policy. Tools should be designed for situations, not the other way around. But instead of embarking on the long overdue redesign of the setting of NATO, a lot of western politicians instead sadly try to redesign perceptions of today's security-realities in Europe, trying to make the modern world's security perception look more like the old “them-or-us” type, which existed during the cold war. But there is a better road, which can be taken. The EU does have a constructive other tradition than NATO's “all-out-war-preparedness” to build on, and the EU is still totally far from the over-militarized development path, which the USA unfortunately has taken. The EU has developed a robust and broad civilian-oriented conflict management capability. The EU already has quite a range of experience with civilian “out-of-area” missions. And the EU is already developing in a direction to integrate all these political management dimensions: The civilian capabilities, and now increasingly upcoming, also an EU military dimension.
We must remember, that military is politics with other means, and military should not be a destructive stand-alone option, but part of as a series of differentiated political tools. Not just a “hammer”, but very varying shades and shapes of tools, within a fully integrated political civil-military toolbox. It therefore can make enormous sense to leave the NATO fully over as a new institutional part of the EU. To enable the EU to manage the full range of all political dimensions, in case a non-European conflict might benefit from European assistance: military, civilian and economical.
Some caveats here include the potential issues this would involve especially in relation to France, but a broader context to all the EU countries. An EU-NATO without the USA will, of course, be centered on France, a country with archaeological remains of imperial thinking and ambitions, and its own possible “military-industrial-political” complex, which might take on an arms race of its own. It is also to be avoided to intervene just for the sake of it — be it under “do-good” or imperial intentions. Because once bureaucratic institutions have been erected for any purpose whatsoever, their inner dynamic is that they urge their surroundings to be made use of. These effects cannot be entirely avoided, but might (hopefully) be mitigated by the full range of EU member countries.
Therefore, even taking account of the caveats just mentioned above, there is a possibility that a lot of positive things could potentially be achieved by letting the USA leave NATO and allowing for the rest of NATO to be subsumed into the EU.