The people saying yes are being way too optimistic. If you've seen Intel's launches in the past, you'd know that they typically don't adjust prices very much at all, under any circumstances.
I'm guessing SB might drop in price ~5%, probably all through the retailers own initiatives. Hard to sell a 2500k for $219 when you've got the 3570k sitting next to it at $223.
SB-E, on the other hand, isn't going to budge. IVB is not going to "destroy" the 3820. The 3570k has been benched, and it's about 5% faster than the 2500k.
LGA 2011 and LGA 1155 are totally different markets. What happens in one won't effect the other. People who want a good reasonably priced chip will keep going with LGA 1155, and those who want the best performance money can buy are going to keep going with LGA 2011.