Well, for chips that are, say, twice as fast as the best current chips for three times the money, I suspect that the market is in fact shrinking, because for most people, current chips are good enough.
There's still plenty of people who want more speed badly enough to pay for it, but my impression is that there aren't as many as there used to be.
Or in other words, the market for single-chip performance is shrinking.
The hyperscale folks care about how much physical space given performance takes, but that's likely more energy/performance than chipcount/performance constrained.
Agreed, there's still plenty of people hitting pain with Image/Video processing, 3D development (design or programming), 4K video/gaming/modelling are definitely still out there...
Upgraded to an i7-4790K almost 2 years ago, and while not willing to drop another $1500 to upgrade to the latest CPU/MB, I have been keeping an eye open.
There's still plenty of people who want more speed badly enough to pay for it, but my impression is that there aren't as many as there used to be.