From the looks of things AMD will be moving to a new processor package next year, let's assume this AM5. On Twitter some info was shared and it looks to become at 1718 pin design based on a line-grid array or LGA much like intel uses (no pins anymore).

Socket AM5 would also be a notch bigger. The chips are expected to offer support for dual-channel ddr5 and, of course, PCIe 4.0. Yes, Ryzen seems to be sticking with PCIe 4.0. It was expected that the Raphael and Rembrandt generations would already use PCIe 5.0 for AM5.

• Dual-channel DDR5
• PCI-e 4.0
• 600 series chipset

This could also entail motherboards based on a 600 series chipset. The information provider is ExecutableFix, who built a reputation sharing pretty correct info like this. However, take it with a grain of salt as nothing has been confirmed even remotely. ExecutableFix also confirmed that the AM5 CPUs still have to do without PCI-e 5.0 - the latter is reserved exclusively for the Zen4 Genoa (EPYC) processors. The size of the CPU package should remain at 40mm of AM4, while the manufacturing process takes place at 5nm.

When AMD will bring the first AM5 CPUs onto the market remains to be seen. Rumor has it that these processors will run under the code name Raphael at AMD and appear sometime in 2022. 

Alleged specifications of AMD AM5 emerge: slightly bigger than Intels counterpart and DDR5