Coldfire* is mostly binary compatible with m68k, only a few instructions/addressing modes need to be trapped and emulated. Also asm can be re-assembled without modification because the removed instructions can be replaced by exactly equivalent sequences of other instructions, and even bytecode can in some cases be reprocessed.
But if the OS was entirely Coldfire compatible, we could at least do something. Also there are bigger differences in supervisor mode than in user mode I believe, which most application software won't touch.
Just an idea...
*Version 4 even adds back some of the instructions originally removed