I think you're missing something here. In what way would they bump the imac? Thunderbolt specs aren't increasing anytime soon, and when you do see an increase, it may not be that great of one. It may take many revisions and generations for it to match what you can do today simply via pci cards. On bumping the imac, what would you do? The top cpu option is the second fastest in that socket type. The fastest is only slightly faster. Regardless of what you do, I doubt you'd notice the difference. It's a case of if the 2600k won't do the job, the 2700k isn't going to change that. On gpus, they're not going to fit a significantly hotter one in there. They currently use one that was designed for heavy laptops. Heat is likely to be a limiting factor there. I guess they could eventually ditch 3.5" drives and maybe force in 3x 2.5" drives, but that won't make a big difference today. It's unlikely that the controller could fully utilize that amount of drive bandwidth.
This is my point. What could you really bump without a drastic redesign? Also yeah Apple likes to use "powerful" as a buzz word, much like "retina".
I guess you could try to edit it on an imac if you don't expect it to play back in real time, but it doesn't sound that fun.