As far as my limited knowledge goes without checking, ARM builds for major Mac software is already the norm for commercial software, but the lines get blurry sometimes. Just a guess in the blue, but I think if compatibility exists at a library level, it might take long until requiring ARM-specific builds for all code becomes mandatory.
IIRC the previous version was a cost for Apple due to licensing agreements or something, but in general they are not so big on retrocompatibility (and nowadays it’s “legal” to have a VM which runs an earlier version of macOS, which could let you run Rosetta 2).
I wouldn’t be surprised if Rosetta 2 stopped existing “soon”.
Windows arm64 has a very interesting approach to the same problem: the ARM64EC ABI provides 1-to-1 mapping between x64 and ARM registers, so that an x64 program can link to a ARM64EC library. It blocks you out from additional registers sadly.