It's believed that the current Vermeer lineup will be succeeded by Warhol, sort of a Vermeer refresh made on a 6nm process with Zen3+ cores. Vermeer will stick with AM4 and should hit the market later this year. So far, AMD has yet to publicly confirmed this refresh.
On the APU front, there's news about Rembrandt and Phoenix. The current Cezanne APUs will be succeeded by Rembrandt, which is expected to pack the same 6nm Zen3+ cores. Rembrandt will likely be the Ryzen 6000 series, it will stick with PCI Express 4.0 but is believed to support DDR5. This model uses the new FP7 socket.
After Rembrandt, we can expect Phoenix. That future APU, likely Ryzen 7000 series, will reportedly use the FP8 socket. Phoenix will get DDR5 support and may also have PCI Express 5.0 support, the latter isn't confirmed yet.
Zen 4 is expected to up the core count. With the Zen 3 generation, AMD didn't increase the number of cores because the firm didn't think it made sense yet. There are rumors that the Zen 4-based Genoa server parts will get up to 96 cores, an increase of 32 cores versus the current Zen 3-based Milan. As such, the Phoenix APUs may see core counts of up to 12 cores.
Raphael / RPL / A60F00 / AM5— Patrick Schur (@patrickschur_) February 18, 2021
Phoenix / PHX / A70F00 / FP8