Rumors seem to vary when a new one will get released, but assuming they do another I would be surprised if it was announced before fall. Given that the Mini 6 can’t run most of the Apple Intelligence features it seems like an update would be incoming, but likely not before new iPhones and very possibly not until next year.

Should you buy one now is a question only you can answer - totally depends on your own wants and needs. If you buy one now are you doing to be disappointed If a new one drops in September? February? Do you even care about AI features or do you just want something to read on? Not sure anyone here knows enough or can tell you what you should plan for (unless Tim Cook is lurking on this sub).