AMD will have a refresh to the current Zen 3 Vermeer Ryzen 5000 CPUs in the form of Zen 3+ Warhol some time in Q4 2021. Warhol will largely retain the existing Zen 3 feature set but is slated to offer a slight IPC bump in order to compete against Intel's upcoming hybrid Alder Lake-S offerings.
https://www.notebookcheck.net/AMD-Ryzen-Zen-3-Warhol-likely-to-launch-in-Q4-2021-modest-IPC-bump-on-the-anvil-to-take-on-Intel-Alder-Lake-S.519411.0.html
Why would amd need to do a refresh to compete with an inferior CPU like Alder lake.
The only benchmark I have seen for alder Lake suggests its on par with a 9900k.
Rocket Lake is a superior cpu (in terms of performance) to alder lake and that looks like real competition for AMD 5000 Series in lower threaded apps, games etc.
I think maybe amd wants to test the waters with a new socket, ddr5, pcie 5.0 with zen 3+ before updating to zen 4. So zen 4 would have a socket that's ready for it.
Though it might not be the best comparison, Bristol ridge used am4 too.