If we see a redesigned MBP at WWDC (which I fully expect), or at least one that includes USB-C with TB3 (can't imagine that NOT happening), then I also fully expect USB-C w/TB3 to proliferate throughout the Mac lineup following its intro on the new MBP's, similar to how it was rolled out originally in 2011. Between that, the massive GPU improvements due to the new 14/16nm processes, and the (nearly) 4 year old design of the current iMac, I think we'll see new iMacs in the fall, probably with Kaby Lake, that will be a significant advance worth waiting for; something that will give a sense of future-proofing.