I would adapt. I'd build a pc as my main rig, keep my cinema display and maybe get an iPad/Macbook Air to quell my thirst for Apple. It would be a dumb idea on Apples part. I don't think I could go back to the iMac after using the Mac Pro. They run way too hot and they're a pain to open up.
I already abandoned ship. Sold my 2008 while I could get something for it and built a nice westmere system. Just installed a ATI 6950 too. My mini keeps me connected to the apple would. Won't pay much more to do it.