There admittedly aren't many for "intensive number-crunching that needs to happen in the client even though a server is almost definitely available, and which a

There admittedly aren't many for "intensive number-crunching that needs to happen in the client even though a server is almost definitely available, and which also can't directly interact with the DOM". Games and cryptography are the only big ones that come to mind right now (for example, services like ProtonMail that do client-side decryption). Hopefully the DOM limitation (and general API limitations) will be lifted over time, in which case there could be a huge use-case for client-side rendering which can be a bottleneck right now. Lifting the API limitations could also allow the web to become truly multi-lingual; you could ditch JS entirely. But other than the above, you still have the question of "what computation really needs to be done in the web client when you have a server on-hand?" Even in Electron, you have the ability to spin up other processes on the host machine. I think WebAssembly is super cool but it still needs a killer-app. Ironically, one of the places it's really getting some interesting traction is on the server. It's like a JVM without a garbage collector. I look forward to seeing where that goes.