Thanks for this. An editor just asked me what might happen, exactly, if NATO collapsed. Here's one of dozens of plausible scenarios that occurred to me, although I hadn't worked it out to this level of novelistic detail.
Something like this, however, was the first scenario I imagined. There are many more scenarios all-too-easily imagined. None of them are good. But think "Sudeten crisis+information/hybrid warfare." 
Worst case scenario probably involves ethnic Russians outside of the Russian federation+far right+far left+devastating cyber/information warfare. A too-late realization that we *don't* have peace in our time leads to Russia "de-escalating" the conflict...with nuclear weapons.
"Where would you get that idea, Claire?" Oh, from reading what Russia explicitly says it will do and watching what it *has* done for more than a century. But apart from that--just my imagination.
