Microsoft isn't gonna let that get away, you can bet on that. And even if they do let "MS-DOS" get away, they'll hold onto "MS" as far as it regards computer software, so it'll just go from being "MS-DOS®" to being "MS®-DOS".
I'm currently wracking my brain trying to port the code away from...
For what it's worth, I decided to call my fork "PC DOS/RE", since as far as I can tell, "PC DOS" was never trademarked.
And this is, after all, both MS-DOS 4.0 and PC DOS 4.0.
To be fair, there's Patched ROM 14, which provides the same things I'm providing. And the Nabu company's been dead for decades. But there's always a successor in interest and I'd prefer to take the safe approach rather than suddenly have some megacorp that bought out some other megacorp that...
This is certainly a case of "coder is an ID10T", but last July I tried to write a floppy disk bootloader for the Nabu that:
Doesn't use the official code, because I want it copyright-clean.
Can boot existing CP/M 3.1 boot disks.
I coded it in two forms - one that is part of my boot ROM...
I can't remember the 0xCF (DF, EF, FF) voodoo, or where I read it. All I tried to do was read head 0, track 0, sector 1 to 0xC000 and run it.
It might actually have been the Ishkur bootstrap or something, or perhaps MAME. My memory's failing me. :/