Angular, React, etc. are nothing but a bunch of pre-written lines of code that does data binding. Quality lines of codes with a lot of candies, but in the end it's only a bunch of JS lines.
There are no obligations whatsoever to keep your project cutting edge and even less of reason to migrate to a more popular framework. It's not as if browser support for Angular 1 would stop.
It is, but you have to balance it out. Updating an entire app to a new major version (without backward compatibility) simply to use let's say a new API wrapper or syntactic sugar is a waste of time. If the app works fine, there's no need to migrate.
