I dont think we're going to go back to that anytime soon, the performance hit is just too big compared to a well written js implementation.
To be fair, Blazor uses wasm, which is significantly better then the cross-compilation of GWT back then. nonetheless, the performance (esp. time to first render) is just not good enough for a lot of consumer facing apps
It definitely has its niche though. Especially if you're able to cache the .net runtime that gets executed through wasm locally (PWA style)
I've built frontends in React and feel I have a fairly high level of expertise in VueJS; I actually got the sense that Blazor borrows quite a few ideas from VueJS. A major missing component IMHO is a good reactive state store like MobX..