I hope that this will be wildly accepted and not end like many other good things with "you know, our code currently 'works' .. why would we invest so much effort to make the compiler happy?"
Microsoft is currently updating a lot of code to add this feature, in the end the community will pressure the libraries author so they do the same.
I guess that in a few year all popular libs will use the nullable feature.
See also: adoption of TypeScript in the JavaScript community. There is pressure from the ts community for libraries to either be created in ts or for popular libraries to adopt it, and it's become the way a plurality if js devs write js very quickly.
