I wouldn’t expect to upgrade a machine like the Studio every year anyway (even if Apple deigned to update it that often). I’d guess most buyers would be expecting to get at least 3 years out of it, unless they were pushing at the bleeding edge of performance.
The main purpose of any “M2 bump” would be to keep the product fresh for new buyers. In the case of the MacBook Air, the bump has come with a major new case design and new display - but what are they going to do with the Studio - change the colour? Make the lid plastic?
Anyway, it’s a bit too early to call: we don’t know what the “M2 Max” and “Ultra” are actually going to be - especially bearing in mind that some of the “new” M2 features vs. the regular M1 - LPDDR5, the extra hardware codecs - are already in the M1 Max/Ultra. The slightly faster CPU and GPU performance would be nice, but probably not compelling. On the other hand, if there’s a significant increase in the number of cores, that could tempt some people. Plus, whereas the rumoured MBP update (if it even happens this year) is probably going to be 5nm the Studio isn’t even 1 year old until next spring, by which time 3nm chips might be in play, which might make a more compelling upgrade.
Also, anybody currently hitting the performance limits of the Ultra is probably going to be waiting for the Mythical Mac Pro - although I have a wild theory that the new MP will turn out to be, effectively, a M? Studio Ultra in a 1U rack mount case (Want more power? Cluster them! Put 6 of them in the space occupied by an Intel MP).