So basically i9 = i7 in the upcoming Intel's generation. Of course, i9 may be better-binned chips, but I believe both would behave within 3% when OC'd.
Judging from the other leaks, Intel's Peltier cooling and the motherboards with the beefiest power phases good enough for 64-core Threadrippers - those are gonna be VERY power-hungry and hot. Some leaks suggest that i9 would be up to 250-300 W on its own when OC'd. So this would result in much higher expenses for cooling (air wouldn't literally work), PSU power, overall heat generation inside the case, and shorter overall lifetime. And those ultra-expensive Z590 mobos will be short-lived since the next generation will have DDR5, and since the CPU core limit for that generation is limited to 8 cores (even Comet Lake is more future-proof with 10/20 top CPU).
Stupid "new" generation, to be honest.