Fair enough. Who knows what Parallels or MS may cook up. I just don't see it being a smart move cost wise for Parallels, and nay sales for MS would be rounding error and not worth the costs.
I‘m sure Corel (owner of Parallels Desktop) would be willing to be an “OEM” for Windows on ARM. It would open up enterprise sales (no large business is going to deploy Windows on M1 Macs while Windows licensing is at best ambiguous). Also, it would ensure that there is a viable business model for Parallels Desktop. As it stands, Microsoft can crack down on Windows on M1 Macs at any time if it wanted to.