N5 is already showing better yields compared to N7 and N10 going by production times, and TSMC also plans to squeeze two more nodes in between N5 and N3. N5P is supposed to start volume production some time in 2021, while N4 should become operational in 2022. The surprising part is that N3 scheduled for 2H 2022 will not use GAAFET transistors. Instead, it will be based on some sort of improved FinFET tech.
https://www.notebookcheck.net/TSMC-releases-more-details-regarding-the-upcoming-3-nm-node.489515.0.html