The rumor is that this hypothetical (first out the door on M4) Ultra will be an entirely new chip... on N3E and uniquely designed to be the new single chip Ultra- no more linking two MAXes together.
Rumor order somewhat flips:
- M4 Ultra first, then
- M4 PRO & MAX months later, then
- M4.
Why? Rumor says Ultras are the most profitable Macs sold... but they are getting the least time in the (desirability) limelight because soon after, the next M++ launches... implying the M++ MAX is only a few months out... and it generally overcomes many of ULTRAs advantages. Flip the order and ULTRA is King of Mac power for the entire year+ until the
next Ultra is launched. If the profitability part of the rumor is true, Apple makes the most money from those sales for the whole year instead of only a few months... when the "as is" approach puts Ultra in that "king" slot... and everyone knows it's the last of the M<current> line.
In this flip rumor, those waiting for the cheapest M4base Macs would be buying at the end of the M4 cycle with rumors of M5 "coming soon" cranking up. Look in any transitional threads with a next generation upcoming and you'll see lots of posts of techno-angst about not wanting to buy "old technology" when "newer" is impending. This very concept somewhat impacts Ultra now because it rolls out last (so far).
Many think they see a set-in-stone pattern in only 3 iterations so far (only 2 iterations of ultra) but that's a pattern only if Apple sticks with it. Flipping the order is simply a choice... like rolling out M3 + M3 PRO + M3MAX all at the
same time... and/or sticking a M3 in a MBpro case and calling it a MBpro... or sticking M-series chips in iPads and breaking a long-term pattern of using only A-series.
There's no confident pattern until we're seeing maybe M6 or so... and even then, that pattern can be broken by simple choices to disrupt it. I'd generally guess Mbase, then Pro + Mac, then Ultra persists... except if that maximum profitability bit of that rumor is true, as I'd expect modern Apple Inc to do about anything for a new buck(s).