From what I've seen, Broadwell-E "will be compatible with current generation X99 motherboards that feature the LGA 2011-v3 socket." (Citing reference)
I've been tossing around the idea too, but might wait for more data. Those prices on the 5820K and 5930K at Microcenter are pretty tempting...
Thought this was a pretty good deal: Corsair Carbide Series Air 540 High Airflow ATX Cube Case CC-9011030-WW - Black for $100.99
http://www.amazon.com/gp/product/B00D6GINF4
Not sure it's enough to justify upgrading from my i7-2600K either. I think I'll spend the money on new pipes for one of the bikes instead. Will see what things look like next year with DX12 and such.