There was a rumor predicting initial shortages with the new imacs. It's unlikely that these would be cpu/gpu shortages. They're more likely related to assembly, including the updated display process. I wouldn't expect anything until that initial surge passes. Beyond that there are conflicting factors. It's arguable that Apple would want some amount of uniformity for those using imac + thunderbolt display. This could be a very small percentage of sales though. The other thing is whether they want to continue the cinema display that has remained in production for pre - 2011 Macs including the Mac Pro going forward. There's no real guarantee of thunderbolt in an updated mac pro, given that it would take some extra engineering work on Apple's part regardless of what cpus are used. It doesn't matter if they're Sandy Bridge E or Ivy. Apple's priority for displays hasn't seemed too focused on the mac pro crowd, but I don't know if that will change again. Apple displays were quite popular in that market segment for a while there around the time of the aluminum cinema displays, but that dropped off a long time ago.