What would The Who have been like with Ringo on drums and McCartney doing bass?
Less exciting without Moon's drumming (compare the Who albums before and after his death to see how irreplaceable he was) but I can imagine McCartney being an asset. I don't imagine he'd have stayed very long though.
What would The Beatles have been like with Moon doing drums and Entwhistle on bass?
Less varied vocally and more cynical - Lennon would have ended up doing a lot more of both singing and writing. But it'd have been fun to see Lennon and Harrison try to cope with Moon's drumming.
(*) Prior to seeing Bent, which had lots to like - particularly Alan Cummings clearly being delighted to be queer on stage - but which didn't move me in the way it has others. It was full, which it certainly deserverd to be, and I was very impressed with the fact that everyone looked to have returned for the second half.