storage and PCIe 4.0 is different topic than CPUs. Yes, it's totally correct that GPUs and storage today CAN NOT benefit from PCIe4.0.
Ryzen5600 will be definitely better than 3600[x] in everything and it should be better than 3700[x] in almost everything except some perfectly scaling multi-core workloads. Six cores with ~20% IPC improvement are equal approximately "7.2 old cores" so 8core 3700 still should be a bit better in workloads that scale perfectly (rendering, number crunching etc).
In very identical way, old ryzen2700 was better in 100% cpu compute intensive tasks than ryzen3600.
We also have to be real : how much your time is spent with 100% cpu utilization ? How much do you render, how long are you able to load up your CPU at 100% ? What happens if your render/compute tasks finish 15 minutes later ? you can multitask, leave it running in background and do something meaningful in the meantime. If you are not earning money with your CPU intensive tasks, it's moot point of hunting the best.
Recommendation has been provided. Just wait for benchmarks - there's nothing else you can do today, right ? Don't decide on anything today, you have no data in your hands, that's it. Also I expect these new CPUs will not be realistically available the whole November and maybe even before Christmas so the question might be if you can/will wait so long (AMD sure will push higher-priced 5900 & 5800 because they will earn more money on those, as simple as that). Next, there for sure will be a price premium on 5600 compared to 3700, it might be $100 more expensive which is very significant in this price range ! Where I live, I can buy 3600 for 175 eur with tax today ; 5600 are announced for $299 so they will go for about 350 eur realistically... and this is huge difference most likely not worth it.
Also, one thing : ". I have an older Radeon hd 480 that I could use for now"
Apologies, I don't get it. You want to use this GPU for gaming on Ryzen 3700/5600 ? That would be terribly, terribly wrong decision. I guess you decided on buying new GPU when it's available, and
Depending on the price, I'm most likely not spending 350eur on Ryzen5600 CPU : FOR GAMING, BETTER GPU with good ol' 3600 for 175 eur with MSI X470 priced 100 eur is better. Compare that combo to B550/X570 costing 175eur to be reasonably worth it plus 320-350eur Ryzen 5600... that's about 250 eur of savings !!
x470+3600 == 275 eur
b550+5600 == 525 eur (estimate)
What a terrible difference !! For gaming, faster GPU any day and the final result will be better than with faster CPU.
What we don't know yet is the memory frequency performance scaling on new CPUs. Might be interesting, now that we have much better cache & prediction modules & IPC...