The problem is that most cpu architectures name it x86, power pc, arm, ... all are hitting some kind of wall in single thread performance where all architectures perform about the same.
Except we aren't.
We're making CPUs pretty much the same way we had been for decades - using silicon. That's what is hitting a wall.
But we've known alternative semiconductors for years. They're being developed mostly by research institutions, so it is a slow process. Once big enterprises take the leading role, we'll probably see some actual products.
It's not just about single-core performance either. Density is a real problem and we're already experiencing it.
Think about 3950X. It needs fairly robust cooling to stay under that 95*C limit.
Even if AMD can sell such a CPU for $150 in the future, it could never be accepted as a mainstream product, because there's no way to cool by the kind of cooling small OEM desktops offer.
But the solution is extremely simple. You make a similar CPU on a silicon that tolerates higher temperatures.
You end up with a CPU that still uses 100-150W, but with cores that don't mind 200*C. Hence, you don't need a 240mm AiO anymore. A decent slim air cooler will do.
The differentiation is long ago outside of that single thread performance, its the number of cpu cores, power (consumption), features, integration (soc/accelerators/gpu/...), ...
It's already 2020.
It's
precisely 2020, not "already". As I said: at this moment improving CPUs by adding cores is cheaper and still makes sense.
That's because even with mixed, casual/work scenarios it's not that hard to benefit from 6-8 cores, and we've only getting to that in the mainstream segment.
But now, going to 12, 16, 64 cores etc - a lot of people won't see a significant improvement.
People who are dependent on single-thread loads will not accept being stuck in 2020. They'll gladly pay a premium to see some progress.
So who knows - maybe the CPU market will fork? We'll have CPUs with less but faster cores (probably very expensive at first) and CPUs with more but slower cores (probably the more "budget-friendly" option).
Maybe heterogenous processors are the answer. If I could choose between a 3950X and a "3700X with extra 2 cores hitting 8 GHz", I'd certainly take the latter. Even for the same cash.
This is no longer the Sandy Bridge era, both vendors considerably improve their offerings every year, and today's $300+ CPU is very likely to be matched and/or beaten in one or two years by the $200 model. People looking to maximize value over time will buy according to their needs and upgrade more often, at equal or lower TCO.
This only applies to DIY PCs (so like 5% of the market?).
For most consumers and companies a PC that is expected to last for as long as possible, with 4-5 years being a typical lower limit.