The way I see it at the moment is if you go for a 2600k with a gen 3 1155 motherboard you can upgrade to Ivy Bridge later on.
If you go with a 980 you have no upgrade options and no PCI-E 3 plus it's more expensive than a 2600k which performs better and you still have enough money after buying one for a gen 3 1155 motherboard.
If you go with a 3820 you have options to upgrade to the high SB-E CPUs and possibly IB-E next year.
The thing with IB-E being compatible with 2011 and X79 though is although it may be compatible i'd put money on Intel releasing a separate chipset for IB-E when it is released.
Just go with what you think would be best for you