Given many new handhelds coming on the scene and general disinterest of Microsoft to support the market, do you think SteamOS will take place of default OS the same way Android did on phones some time ago?
This is a weird comment to me, SteamOS could have an ARM build, Valve would just need to release a ARM build of their distro (and Steam for Linux).
There's definitely ARM for lots Linux software and distros, so assuming Valve hasn't done anything particularly weird, aside from the build infrastructure, that's probably not even that big of a job.
There are several other emulators that already exist for Linux (that they could contribute to/improve).
Ignoring that for a second though, this is a problem for Windows handhelds as well. If Valve was going to build up the ARM "PC" gaming market though, they'd need to start with making ARM Steam builds available.
Edit: I'm guessing those ARM handhelds aren't making Valve money and are probably more for emulation themselves (i.e., for Valve to do this, they'd need things in place to where it would benefit them via sales in Steam).
Wine already existed but it took many years to get Proton to where it is now, and it's still not perfect. I doubt they would want to start all over now that things are finally working.
I'm not sure where you're getting the idea that they'd start over. Wine isn't an emulator and doesn't emulate instructions. Something like qemu-user would presumably run Wine (which would itself be running the game).
In a way, Proton/Wine is a much harder problem because there's so much in terms of API that needs implemented.
I meant that it would be a whole another problem that I don't think they would want to address right now, considering that they're still fixing Proton. Creating an ARM translator with good enough perfomance would take several years, and I don't think they would profit as much from it, they did Proton because they don't want to depend on Windows (which in recent years has become a competitor since Microsoft is investing more in the PC gaming ecosystem).
This would also open it up for running SteamOS VMs on Apple Silicon Macs. I was surprised how few distros actually supported arm I switched over and none of the gaming oriented ones I looked for had ARM support.
Why not for ARM handhelds? I don’t think there is anything that handles x86 on arm well outside of Apple. But there are some things on Linux that can do it.
I’ve not personally tried it though. Maybe I will today, I have a spare raspberry pi that’s not doing much.