Funny, that's what everyone said 5 years ago. I'll bet on React to be here for another decade, no problem - there's just way too much momentum. In a way, it's Rails all over again (that's a positive).
It may not be the glory days, but Rail's is still going strong 13 years later. React, however, has reached a popularity many times larger than RoR ever did.
https://trends.google.com/trends/explore?date=all&geo=US&q=r...
There has never been a project (I can think of), other than the Linux kernel, with the resources that companies and developers have put behind React.
> Do you remember Adobe Flex
Flex never came close to either RoR or React popularity, and was propelled mostly by the dying wave of ActionScript programmers from the aughts after cell phones killed the Flash game market.
[0]: https://trends.google.com/trends/explore?date=all&geo=US&q=r...
Seriously? Adobe Flex was a closed-source and proprietary commercial offering capitalizing on the prior decade's popularity of Flash.
React is open source with a vast and robust ecosystem of even more open source to go along with it. It couldn't be more night & day.
That confirms it: you aren't old enough to remember Flex. It was open source.
> https://trends.google.com/trends/explore?date=all&geo=US&q=r...
I'm not sure this chart is very good evidence of this claim. There are so many other things named "react" -- Nike React shoes, Kids React videos, reactionary politics, and so on -- that it's a bit like claiming Trump.js is the most popular JavaScript library in the world because of this chart: https://trends.google.com/trends/explore?date=all&geo=US&q=r...
If you want a component-based view library that is written in js, and you are happy to take on the task of assembling a build-system, styling system, routing and of course state-management, I can't see much of an architectural improvement you could make over React.
If you want batteries included - go with Vue.
If you want the Ruby/spring opinion and batteries included go with Ember.
Svelte looks kinda cool. But it seems to sit deep in the browser spec, and in my NAIVE opinion, it doesn't seem hold the component abstraction as something even valuable. It just wants you to script away. Which, is just movement within a trade-off space - if it suits you go for it.