What do ppl always have abut the G5? As pointed out several times the G5 is not the best target.
The cpu draws a lot of power, runs hot, the Altivec equivalent is relatively poor and to use it with the ABox is would have to be operated in 32 bit mode (and w/o using some tricks only one core will be used), plus boards are not new, too (and since hot parts are used their expexted lifetime will be lower than "cool" chip based boards like iBook or Mini.
And MorphOS on the Mini and ibook are relativly easy to achieve, the 7447 is supported already.
Plus, the port is quite advanced.
Let's keep pragmatic ad realisti and let the team finish the Mini port (plus iBook maybe) and then it is time to think about what comes next.

But if thinking about hypothetical future plans, let's hope for some 8610 based device soon. IMO the smartest choice for now:
small, cheap, low energy but surprisingly fast.