It's quite possible that ARM Macs will run Windows. Windows RT already runs on ARM, and Microsoft seems to be moving in the direction of embracing alternative platforms (see how they push Azure for iOS). They'd sell more Windows licenses and gain more users, and at worst they'd lose some Surface sales.
Whether Apple would allow it is a different question.
I'd wager most people with a need for running windows on a mac do it to run some "legacy" win32/win64 binary application (and not just iexplore.exe or msword.exe), so an "ARM Windows Bootcamp" mode probably wouldn't solve anyone's problem.
Whether Apple would allow it is a different question.