I know about old tech like gopher, but has there been or is there any project that is developing the replacement for hypertext and the browser? It seems things are heading that way with wasm and pwa's.
It is true that browsers replaced gopher clients. But it wasn't an either or. Until everything became (more or less) Chrome rather recently, browsers handled the gopher protocol just as browsers largely replaced FTP clients. (Opera used to also handle email until it went webkit).
Mathematically, gopher and the world wide web are both directed graphs. In a Turing tarpit sense, gopher could be bent to do what the web does in terms of information retrieval and indexing.
The early web looked pretty much like gopher. Not just CERN but Yahoo! too (and even the HN frontpage today). The web won in part because people wrote for the web protocol by default instead of gopher when the internet exploded in the mid 1990's.
So in an important sense, replacing the web means finding something more useful than a directed graph. That's non-obvious.
In the technical literal sense, the browser is most likely to replace the browser. When a new capability is wanted, it gets added to the browser. The browser has always handled multiple protocols. Browsers that handled HTTPS replace browsers that don't. Browsers that handle HTTP2 replace browsers that don't. And so on.