Xiaomi announced on its MIUI forum today that it is going to be ending development for MIUI 9 with the next update, which is slated for April 27. Xiaomi has successfully pushed out weekly updates to MIUI for 373 weeks since beginning in August of 2010. Now Xiaomi isn't ending development and abandoning phones on MIUI 9, instead it is going to be focusing on optimization and stability. What won't be happening is, new features coming to MIUI 9. Which means that MIUI 10 is likely coming in the next few months - possibly with the next big flagship release, which could be the Mi 7.
In the forum post, the MIUI team also mentioned that it will no longer be supporting devices running on Android 5.x which is not entirely surprising, seeing as its newer devices are on Android 8.x Oreo right now, and Android 5.x (dubbed 'Lollipop') is approaching four years old at this point. That's a pretty good life span for receiving updates though. Considering most smartphones do stop receiving OS updates after a year or two, sometimes less. That's something that Xiaomi really likes to boast about, and it should. Updating a smartphone for nearly four years is nothing to sneeze at.
The team is going to be pushing out the last development/Alpha build of MIUI 9 on Friday, April 27. But those on the stable or beta ROM will be getting more updates in the coming months. The team believes that it will have a new stable version out around June of this year. Which gives them a little over a month to make MIUI 9.5 more stable for its devices. MIUI 10 was not mentioned in this forum post from the team, but it's likely the next step. After all, MIUI 7 and 8 both ended at 7.5 and 8.5 respectively, and now MIUI 9 is ending at 9.5. It'll be interesting to see what kind of new features the company puts into MIUI 10, it's one of the few Android skins that gets new updates each and every week and has more features than just about any other skin out there.