IMHO, it's hard to believe that Apple is going to keep the Studio and Pro on M2 for another year. That would be killing them. And also, I don't think they will upgrade them to M3-class SoCs once the M4 has been released.
On the other hand, I think it makes a lot of sense to release M4 Max and Ultra (or something similar) for the Studio/Pro at WWDC. Just like the M4 on the iPad Pro, the Studio/Pro are much less demanded (and thus, Apple is much more likely to meet the demand for Max/Ultra chips), and it would once and for all start fixing the release cycle for Macs in general:
- New tech gets introduced on a mobile, low demand platform (just like M4 on iPad Pro)
- Pro desktop machines get it next, not much later, in Max/Ultra flavors (Mac Studio/Pro, maybe Mini with the Mn Pro variant).
- Pro laptops are next in line a few months later, in Max/Pro/regular forms (MBPro), together with the Mini if not released earlier.
- Regular, mass produced laptops and desktops are last (MBAirs, iMacs), when production capability is much higher.
Ideally, everything would be presented in even less events (maybe one for Pro and one for consumer machines?), but at least this timeline would make more sense than what we've had up to now, where new generation Mn chips that perform close to the Pro/Max versions of the previous generation are released on non-pro machines six months earlier than in pro machines (the case of M2).
Apple started fixing this with the M3 launch, where Pro laptops (and the long-forgotten iMac) were released first, then consumer laptops months later. Maybe they will end turning things around with the M4.