I want browsers to support a bytecode language designed from the ground up specifically for this purpose instead of just being a quick hack that by a fluke of history happened to get wide adoption. It would be more like .NET and the JVM in the sense that it would be designed for a specific purpose (a language suitable as a target language for compilers from a wide variety of high level languages). But we should not confuse that last sentence to mean that it should be similar to .NET or the JVM. I think two main design goals should be efficiency and good support for high level languages. This means proper support for tail call optimization so that functional languages like Haskell, Clojure, etc can generate efficient code. It might also mean some special considerations for garbage collection that I'm not knowledgable enough to comment on...amongst other things. WebAssembly sounds like the right idea but if they miss important things like TCO, then it's still not acceptable.