That is a risk on the Windows side for sure. Also, once an ISA becomes popular ( like Apple Silicon ) it will be hard to displace.
Repurposing Linux software for RISC-V should be easy though and I would expect even proprietary software that targets Linux to support it ( if the support anything beyond x86-64 ).
Itanium was a weird architecture and you either bet on it or you did not. RISC and ARM are not so different.
The other factor is that there is a lot less assembly language being used and, if you port away from x64, you are probably going to get rid of any that remains as part of that ( making the app more portable ).