Xiaomi is pushing ahead with MIUI 12.1, the successor to MIUI 12. MIUI 12.1 has already been issued to beta testers, some of whom have outlined what to expect from the next version of MIUI.
https://www.notebookcheck.net/MIUI-12-1-Features-of-Xiaomi-s-next-OS-update-outlined.482424.0.html