Xiaomi has announced its release schedule for MIUI 12, and it includes forty devices. Arriving on handsets as old as the Mi 6, MIUI 12 will start rolling out at the end of June. Beta enrolments start today, though.
https://www.notebookcheck.net/Xiaomi-announces-MIUI-12-update-roadmap-and-it-contains-over-forty-devices.463051.0.html