React has already jumped the shark, people just haven't realized it yet. The backlash will be big. I think most people will jump to Preact or Vue.

The standard tech cycle:

1. Awesome new tech,

2. Tech gets more and more popular,

3. Tech gets more and more features to better cope with new use cases,

4. People get sick of bloat and create awesome new tech to replace it,

5. Go to 1.

The fuse is now lit for lots of apps currently working fine in production to be suddenly labelled 'legacy', and nobody wants to work on the crusty old React or (heavens to Betsy!) Angular anymore.

In 5 years time earnest conversations will be had about trying to find somebody who is willing to maintain the thing, or do we have resource for a complete rewrite?

More details are welcome. React seems to be doing fine and why Preact and not Solid for example?

Angular appeared to be doing well until React appeared and suddenly nobody wanted to touch it. People even accepted Angular 2's docs prioritizing DART. People accepted that DART was the future, at least until the moment React appeared and people had an alternative. Don't underestimate the power of pent-up demand.