The price will come down and maintain a similar relationship between the 24-70 II and the 24-105. The 24-70 II has already come down by $250. If one doesn't want to pay early adopter pricing, wait for the price reductions that are sure to come. It'll probably be cheaper as a kit lens for the 6D too.
For those who want better wide open performance, you have to pay for that. The 24-70/4 IS looks like it beats the 24-105 across the board in this respect. Couple that with a "macro" feature and a Lens Cap II, it could be worth the price.
5D2, D3x, D800E, TSE17, 100L, CZ 18 ZF, CZ 25/2.8 ZF, CZ 28 ZF, CZ 35/2 ZF, CZ 50/2 ZF, 14-24G, 24-70G, 24-70 II, 24-105, 70-200/4 IS