WSL1 is _not_ deprecated. it is just recommended you use WSL2 since theres a wide range of incompatibilities in WSL1 with various Linux tools. However if all you need is a basic toolchain in some ways it’s superior to WSL2 because it doesn’t require a VM.
You are right although in my mind it is frozen, and given Linux continues to move, I see WSL1 has almost deprecated.
For a few years it may continue to be useful, however soon enough you won't be able to run a modern distro on WSL1. At this point it would actually be defacto deprecated.
Thus probably nobody, neither MS nor 3rd parties, will base a medium/long term plan on WSL1 now. It's already legacy tech; still maintained for essential things (security, etc.), but already legacy.
