8700k overclocks to 5 ghz, so the 8 core may approach that. Can't imagine that it won't overclock higher than zen+ which struggles to reach 4.1/4.2 all core. Bigger question to me is the price. Will they price it like current 8700k/2700 and lower other prices, or will it be 400.00 plus.
In an ideal world, the '9700K' should slot straight into the 8700K price point, which is what Intel has done in the past when releasing a new gen of i7 K SKUs. That said, I think the 8700K MSRP was $20 higher than the 7700K, so it's not always an exact swapover.
So I'm hoping it will cost around the same as a 8700K, but even if it was $400 that will probably be justified compared to say, a $330 2700X. AMD will probably drop prices by then though, and possibly release a 2800X to be more competitive in reviews. At the end of the day I'm just glad that we now have a truly competitive landscape in the CPU market.
Finally, that is very cheeky of AMD if the rumours are true of the z490! I was thinking it was another Intel chipset haha