No matter what language I use, no matter what platform I deploy to, if I want to interact with a service or with infrastructure, I'm going to have to use the provided API(s), WASM included.
If I deploy a pre-compiled binary to an AWS Lambda and an Azure Function, and it works on both, it's because I had to have that in mind when I wrote that software. Will that not be true for a runnable WASM binary? It sure seems like it would be true that I would need to detect which platform I'm running on and then execute the proper stuff for the detected platform.
If all APIs are going to be compatible with each other, so that, say, storing a file uses the same API call no matter what system or platform you're on (never going to happen; bear with me) implementing that in WASM outside of the browser does not suddenly make it possible.
This is an opinion, and on HN this is likely to be a very unpopular opinion. I don't expect anyone to adopt this opinion, nor do I expect to sway anyone's thought with this opinion. This really (really, really, really) feels like JavaScript/web people wanting to do things outside of the browser, with performance better than JavaScript alone can provide, and then, rather than simply using an existing language and runtime, deciding that the best route forward is to pave their own road to this destination with web technologies. This does not feel like the best route to take if you want to write software that performs well outside of a browser.
There are lots of other languages, runtimes, and platforms, that allow this today. And the web is a bag of chaos: I can't even get a consistent design or UI language across major websites, today. Buttons sometimes look like links, links sometimes look like menus, and buttons sometimes look like any of those, but somehow WASM outside of the browser is something everyone (except me) can agree on?
I'm skeptical that this is a good idea for anything serious.
Just like there are implementation problems with Java, there are going to be implementation problems with these runtimes that every platform is going to need in order to run this code, now. There are going to be many security concerns because (warning: incoming opinion) nearly all developers are terrible at thinking about preventing security vulnerabilities. Those same developers are usually OK when it comes to fixing them, and terrible at thinking about vulnerability prevention.