If u check tomshardware, even 2x7970GE are not able to bottleneck a bulldozer, let alone 2500K or even 3930K.
U probably gonna need something like a single Nvidia GTX980 to make 2500K bottleneck it. With Direct Compute/Open CL coming, u probably will see more resources shifting toward GPGPU.
Nope, you cannot say it like that.
First, it depends entirely on the game. Second, it matters what fps you need. There are many games out there where a Bulldozer or Piledriver cannot maintain 60fps, especially in tough scenarios.
Bottlenecks don't matter as much as people think. If your GPU(s) can do 35fps, your CPU 50fps but you need 60fps maintained (not average), the knowledge that your GPUs are the bottleneck are of little use, because that doesn't make your fps any higher. In this example you would not be able to get 60fps, no matter how many GPUs you put in there.
Bottlenecks are important, but they don't represent the whole truth. fps is what ultimately matters.