Given that both Ryzen and Rocketlake will have decent IPC gains, I'm fairly confident RKL will be significantly faster for gaming much like current gen. Pretty sure 5.3 all core (or higher) will be achievable on RKL where as OC is rather limited with AMD.
That said, 4900X will clearly be the better buy. 12 vs 8 cores is a hard sell for Intel.. Have had my 10700k as place holder for 4 months now, certain I'd be dropping RKL into this board, but the value just isn't there..
I must be getting old, I've gone from planning an RTX 3090 + RKL build to most likely a far more sensible RTX 3080 + 4900X machine. Sure it's not as fast, both CPU and GPU, but they are incredibly smarter options.