Thanks for those links. I did vaguely remember seeing them in the past but couldn't recall where.
The problem is, they support my view that the TDP figures look wrong. If the uncore (Infinity Fabric) is taking up a pretty static amount of power, that barely rises with additional cores, then each additional 4c should only be adding incremental amounts of power, yet we see a 10w difference between the 3600X and the 3700X, followed by a 30w increase to the 3800X. Sure, there are marginal base clock increases to go with the core increases, muddying the numbers a little. However, it's the scale of the increased power relative to the clock bumps that is screaming out to me that the ACT really can't be too much higher than 0.3GHz above base, unless the 3600X and 3800X have conservative TDP ratings. The 3700X looks like it lines up nicely with the rest of the product stack.
4.6GHz ACT on 16c would be immense though, especially combined with the expected 9-13% IPC increase for Zen 2.
We'd be looking at a 20-25% better performing CPU (in MT tasks; ST would be even better - 31-38%), and that's before we consider the doubled core count for the 3800X.
If all of this is true, I don't see how Intel could possibly compete for a few years.
For me, it seems too good to be true, but from all the information that's available it does at least seem feasible.