Since there's still no official announcement about the Mido EOL status from Xiaomi I expect that they will still release ROMs.
I tried, used and tested hell a lot of MIUI based and non-MIUI custom ROMs but I have to tell you that the performance vs. the battery life and the appearance of the Xiaomi.EU MIUI 10 stable ROM is really good for me, totally meets my expectation against the phone, I don't really miss anything from the ROM and it is actually stable (no Wifi drop issues, no cell radio related issues, no apps force closing, no weird behavior experienced by myself, etc). I'm using some tweaks, tho, but those are really easy to apply (with some Magisk Modules (ie. Mido optimized thermal engine and Swap torpedo along with some I/O tweaks in Kernel Adiutor) the system just flies even better - but I have to admit that even the base ROM is also a really good system).
So what I personally advise? Make a list of pros and cons, look around in Youtube and XDA, read the list carefully and decide: will it be measurably better and/or beneficial to worth it? Or do you want to try something new? You desperately looking for novelty because you are bored?
You will spend a lot of time to create your recreate your environment again. You will get updates in every one to three weeks normally, with all security patches. Probably you will experience some bugs, just like with the MIUI dev. ROMs. Themes are working differently in custom ROMs, you have to look around to check how it works. All in all: you have to expore them and rebuild your phone - but it will have better battery life for example, for sure, better performance, for sure, more "clean" system.. yes.. but if you think you will miss MIUI after all.. you will have to reinstall everything
So.. the security patch level in V10.2.2.0 is 2018-12-01 thus I -
personally - expect a new stable version or the EOL announcement sooner or later.. in the near future.. in a month or so.. if I were you and don't miss anything from the ROM (app, setting, feature, etc..) or don't experience any bug that you cannot live with I would stay on V10.2.2.0 and we will see.. either a new update or an EOL announcement will be released we will have the choice to either update our Mido running MIUI to V10.x.y.z or just aboard the train of custom non-MIUI ROMs because we don't have other choice if we want security updates
Sorry for the long posts.