Intel is in no way losing the HPC market. There are lots of algorithms (like all incompressible CFD, so all car/boat design, even sparse matrix multiply) that gets essentially zero benefit of GPU. At most, I'd say half the popular HPC use cases see significant GPU benefit.

Karl Rupp has a very good series of CPU and GPU performance comparisons, recently updated:

https://www.karlrupp.net/2013/06/cpu-gpu-and-mic-hardware-ch...

Most of the "no GPU benefit" stems from algorithms having low FLOPS per byte. Look up Collella's Seven Dwarves for more details.

And even if we assume GPUs become dominant, Intel is going to sell at least one Xeon for every two Teslas; those GPUs need host CPUs.