Or is the 8086k or an 8700k @5ghz going to be dog top dog for a while? The 9700k will have 8 cores, but most likely won't be able to get to 5ghz I imagine. is 5ghz enough to play all games perfectly now at 4k, or are we still limited by the cpu?
It's useless, many processors have a stp around or more than 2000 nowadays. So PCSX2 should be fine even if it use only 2 cores.
Emulators generally are limited on the number of threads that can be efficiently ran. Because timing is such an important part of emulation, you can't just break everything out into separate threads, or else you create wait loop scenarios and actually slow down the program more than if it we're single threaded.