I got hope — against the rumor mill and other odds — that Cupertino Donut will surprise us with straightening their device upgrade timeline and present the whole line of M4 Macs — including Max and Ultra units — at the same time.
Well, if they're updating the MacBook Pro then we'll presumably get M4 Pro and M4 Max (or equivalent) versions of that.
I'm not sure that it is clear that there is even going to
be a M4 Ultra in the old sense. The idea of the Max being a sort of universal die design where you could "chop off" half the GPU to make a Pro or join several together to make Ultra or Extreme seems to have ended with the M3: the M3 Pro and Max are now quite distinct dies, with the M3 Pro being more efficiency-focussed, the M3 Max having more cores
and a higher ratio of performance to efficiency cores, and giving the M2 Ultra a run for its money. The rumors of a new high-end Apple Silicon chip sound more like a NVIDIA Grace/Hopper contender for AI development and services, rather than something for a personal AV workstation.
There don't seem to be any substantial rumours about the Mac Studio. I guess only Apple know how the Studio Ultra and 2023 Mac Pro have worked out in terms of sales or if the whole "ultrafusion" idea has been a flop (The Mac Pro seems to be using a whole second Max core
primarily to get some PCIe lanes and extra RAM...) I wouldn't be surprised if the 2023 Mac Pro turned out to be the last "big box 'o' slots" Mac esp. if Thunderbolt 5 comes along and offers better bandwidth for external PCIe housings.
Personally, I think a M4 Max Mac Studio with various "binning" options would make a perfectly viable Studio range on its own, without waiting for an Ultra chip. If Apple think there is a market for a server-grade Mac they need to
make a ground-up server grade chip rather than trying to glue laptop SoCs together.