I don’t think any Extreme ever made sense. Was likely information that they leaked to employees to determine who felt being a leaker was more important than being an Apple employee. Then, Apple immediately assisted them with starting that journey.Sounds like:
+) M4 Ultra is not cancelled : Still due out 2025_June on N3E.
+) M4 Extreme never existed
+) M5 Extreme has been cancelled (was being designed on N2P)
+) The High bandwidth face-to-face chiplet architecture that Broadcom specialises in and licensing out to Google will now be leveraged by Apple in a new DataCentre only AI chip (to allow huge scale out with minimal DataCentre power requirements)
I speculate this will result in the next MacPro moving from an 2025_Oct release to a 2025_June release with an M4_Ultra (based on 2 x M4 Maxes) and will no longer be M5 based.
I also think the next Ultra will just be a higher performance option like Max is over Pro. I’m likely wrong, but Apple’s already testing their chops(chips) by making variant processors that aren’t “the high end with dead units” but instead intentionally making chips with a unique set of all “live” cores.
Nothing says that any “Ultra” solution MUST be twice as performant as the Max solution. It just has to be the fastest Mac. And, merely by existing, it will be that.