Running f.e. on X86 "68k" is more than competitive. And there is new FPGA based hardware like FPGA Arcade and at least two other projects at the horizon. PPC is for me more strange, rare and expensive and not much software. 68k at least has much more software. And not fogetting much more users and better distribution opportunities.
Except for the fact that you seem to forget we can already run 68K software.
And that not all our hardware is expensive.
I spend less of a Mac than an FPGA system would cost and it runs faster.
AND, there isn't that much 68K software I want to run.
Remember, we are talking about a back port to 68K, not vice versa.