The JVM showed that a runtime can host a multitude of languages, compile to multiplatform bytecode that require only a "small" runtime (the core of the JVM is pretty simple, the complexity is on the stuff on the edges, like the stdlib) to run on anything and can be ported easily to any architecture. WASM is the new incarnation of the idea and if the people behind its specification stop worrying about politics and start getting stuff done, I am almost sure it will become the new "universal" runtime.
Usually, new programming languages have a huge mountain to climb in terms of libraries that are required for everything these days (encryption, multiple data formas like YAML, JSON, XML, TOML and even the old ones that are still widely used in niches, like ASN.1... HTTP, Database Drivers, logging, monitoring, graphics, mathematics, the list goes on and on... we don't really want to rewrite all the stuff that exists... but interop between languages is very hard and sometimes very inefficient unless it's based on a common set of primitives (like Java bytecode... WASM still needs a lot of features like GC and interface types to be a real alternative).
Zig and other languages that have very good and easy interop with C work around this problem. But I think that the future will be a universal runtime, maybe WASM, maybe something else that doesn't exist yet (or that's not yet known to most of us).
