This would be one of worst moves apple can do. Mac pros fit a minority but they still fit a customer base of a certain type of people. High performance work stations, gamers etc. We don't want some crap imac that lacks the expansion and future proofing of a good long term investment. My 2008 mac pro still runs the latest games with ease, cause i was able to upgrade to 10 gigs of ram, SSD, newest video card, all with ease. Say that about any other mac product line. Heck the mac pros are the only macs that even use a desktop GPU, they shove mobile gpus in their imacs and minis and obviously laptops. That just doesn't cut it for me. Desktop performance is everything to me and i wil never have anything but a tower. If they take the mac option away then i will be stuck with a PC plain and simple and install an unofficial OS X on it.
I was keeping my hopes up for an Ivy bridge mac pro next year as a great uprade path, as sandry bridge is at end of it's line now. Personally it'd be dumb at this point to refresh mac pros this late in game with sandy bridge, because that would be a loss to apple with ivy bridge slated to go live in 2-3 months. If anything they need to kill the current mac pro refresh and focus on that. Being the next first high end computer to sport ivy bridge with their buddy intel hooking em up as they did in the past.