I don't think those performance increase estimates are valid for desktop high performance CPUs. If they were, the +35% performance from 14nm to 7nm would result in a 5.4 GHz capable 3700X. I think expecting more than 5% is unreasonable
I always got the impression that that metric implies higher performance at iso design - ie if you simply ported Zen2 to 7nm+ with minimal changes.
Wanted to address both of these at once:
First, let me emphasize again that I do not simply assume that the max boost frequency for Zen3 will see a 10% improvement just because of the new node. If you examine 7nm's behavior in Matisse in particular, you will see that boost clocks struggle as more cores are loaded, often due to hotspots and the effects of an (admittedly often conservative) boost map. A 16c Vermeer (for example) isn't just going to hit 5170MHz boost just because of 7nm+. If it did, then great, but I do not expect such. Maybe boost in the range of 4.8 GHz or so seems more realistic. But if you look at a 3950x running Prime95 SmallFFTs or some other heavy AVX2 workload, the default behavior of the chip will probably put it at around 3700 MHz or so, which is often the case with a bone stock 3900x at the very least (mine does 3770MHz, but it has excellent cooling). If someone told me that a 16c Vermeer could do 4070 MHz (or so) in the same workload, I would probably believe it.
As for TSMC's metric, I'm pretty sure that the performance is isopower AND isodesign. So yes, this assumes an optical shrink of the old design. But! You also have to consider what are the design limitations on clockspeed. If I knew more about the fmax of Zen2, I could comment more saliently on how much of Zen2's clockspeed limitations are related to design versus process versus heat. It certainly appears as those Zen2 is more limited by concentrated heat than anything else. The process loves low temperatures, and if you can keep the die near room temps, all-core clocks of 4.6 GHz and higher are certainly possible. Hotspots make that insanely difficult. So I don't think it's entirely far-fetched that Zen3 will have an Fmax at least in the same ballpark as Zen2, especially when AMD is sidestepping to a new 7nm node that has as a major benefit the option of higher clocks at isopower. It's not like they're going to pull a Kaveri or Carrizo on us where cache design changes limit Fmax versus the previous generation (Piledriver).
In conclusion, I would project max boost clocks for Vermeer in the 4.8 GHz range, with the possibility of maybe 2-4 cores hitting those clocks at once. MT clocks in heavy workloads are the ones that are most likely to see the full 10% improvement.
I really doubt 20% IPC uplift
I'm a bit skeptical there, but I'm willing to let them take a shot at it. 15% would still be exceptional, especially when you consider that clocks under most applications will go up thanks to the new process.