Zen 3 is likely to arrive next year, but CEO Lisa Su has already weighed in on what AMD will bring to is next-generation processors. While switching to 7 nm represented the largest change for Zen 2, AMD has other plans for Zen 3 onwards. 5 nm processes will arrive in good time too, though.
https://www.notebookcheck.net/Core-architecture-improvements-are-AMD-s-greatest-leverage-for-Zen-3-and-beyond-according-to-CEO-Lisa-Su.440660.0.html