Some of you are missing the point of APUs.
HSA is the future for AMD. The problem is that HSA has the chicken and egg problem.
Developers won't make HSA programs because no one has HSA hardware, and people won't buy HSA hardware because there is no software for it.
What AMD is trying to do with Kaveri is grow an install base for HSA compatible systems, so AMD can approach software developers with HSA tools, show them people do own HSA enabled devices, and then the software company will be more likely to support HSA.
AMD's end game is HSA.
7850k with HSA should even beat 4930k. But it needs the software. And as I mentioned earlier, there's a big problem with getting the software or the hardware out there first.
AMD is making an effort to get hardware sold by pushing gaming. Some day they will "flick a switch" and there will be HSA software for all these APU systems that are HSA aware. But for now HSA is just a few really good benchmarks for things a lot of enthusiasts who care about gaming won't run.
FX 8350 competes with 4770k, not 4670k, but only in workloads that scale properly to several threads. 4770k is 6% faster than FX 8350, but FX 8350 is 16% faster than 4670k in x264 (a benchmark I would consider that scales properly with multiple threads.
I'm not sure if that version of x264 is using AVX2, but like I say with everything regarding Intel vs AMD. You need to look at what programs you actually run and if the trade offs of going AMD are worth it.
For me, Blender is the most important thing for me and FX 8350 runs very well compared to Intel's offerings when Intel is just using Windows. I don't care about x264. But some people might care about x264 and not care about Blender.
But my point is that the entire question of "if AMD is viable on the high end" is way too broad of a question. In fact, I'd say it even treads into the troll bait category. It's not much better than saying something like "is Linux even a good desktop OS?"
FX 8000 series is somewhat of a niche product where it can do some things extremely well for the price and some not. But overall I would say that it is capable of competing on the high end, at lest high end of what Intel calls the "mainstream" socket. It really just depends on what you are going to do with your computer.
I know there are plenty of benchmarks where FX doesn't look nearly as good, but my point is that it is a completely viable option if you're buying your computer to (at least) render and transcode video.