Fortunately, there's a good number of P-51s in flying condition out there, so fans should still be able to see their favorites at the shows. The number of flying B-17's, though, is more limited.
Regarding the debate about flying rare warbirds or just displaying them, I think they should be flown, and it's up to their owners, ultimately, in any case. It's one thing to walk around a museum exhibit, and quite another to hear the roar of a Pratt & Whitney or Wright radial, or a Merlin or Allison, and seeing a plane in its element. And I'm saving for next year, to take a ride in "Fifi" at the MAAM's WWII Weekend in Reading. Maybe not in the bombardier's seat, though.
Prost!
Brad