If the i7 2600k and top FX have similar price and stock performance, but intel keeps the best overclocking potential things can go bad. Their success on that price bracket will depend a lot on that.
Phenom I X4s also had great value @stock and were priced competitively to 775s, but the OC potential of a Q6600 was no match and current SB Ks set the goal very high. I hope BD can really dominate a 2600k in multitasking, so it won't depend on that.