Just because they say they need to be more self-reliant doesn't mean they're pulling out of the alliance. Even Trump, with whom I disagree on pretty much everything, isn't leaving the alliance despite his overheated and irresponsible rhetoric. And "quickly becoming unraveled" is not "we want to leave" it's more "there's a maniac in the white house destabilizing everything that has worked for the past half century".
I would not overstate Trump's impact - you will only give him an even bigger head. In reality he is insignificant to policy as he will be gone soon enough. I would say Putin and Snowden were more of an impact.
In reality by 2024 the Bundeswehr will no longer be committing troops to NATO missions outside Germany (see above). If it makes you feel better to pretend that they are 'still part of NATO' then fine.