We don't think the M series chips are going to be used in the 8.1 We are thinking Apple has a brand new chip they've been developing for about 4 years or so specifically for the Mac Pro 8.1
Not sure why on that track when most of the creditable rumors have been that it is highy connected to the M-series.
From the 2020 leaks that there was Jade , Jade-chop , Jade2C , Jade4C codenames for the rest of the M1 generation SoCs. Which turned into M1 Max ( Jade or Jade2C if the codename was for the die and not the package), M1 Pro ( Jade Chop ) , and M1 Ultra ( Jade2C ) . Jade4C failed to surface as product but not too surprising for 1st generation transition under the conditions.
There is the rumor/sighting of the one-slot-wonder M1 Mac Pro. (perhaps Jade4C that never made it into full production).
Followed up by rumor/sighting of the 6-slot-wonder M2 Mac Pro.
In the concrete announced by Apple context ... the M1 Ultra covering the MP 2019 (7,1) in the 16 core most popular 16 core configuration and the most popular W5700 configuration. Haven't even gotten to the "twice as much as Ultra" configuration yet.
So it is not most of what Apple actually sells that the M-series is not covering in performance. It is the extreme outer fringe of the MP 7,1 configurations that they are not covering. The question is that niche of the already around 1-2% Mac market (that is the Mac Pro) is worth going after with a targeted SoC for just for less than 1%.
The Mac Pro 2009-2012 system was tweaked to merge the single socket and dual socket workstation market into one single chassis system for both. There was a time back in 2016-2018 where there was several folks pushing the notion that Apple "had to" come with a dual socket Mac Pro to compete with the largest HP Z8 and Dell 7000 series offerings. In 2019, Apple did not.
Same thing is happening now. This "Apple has to match the biggest Threadripper 5000 and two of biggest firebreathing dragon Nvidia 4090s or it is a "fail" " notion is likely not what Apple's metrics are at all. And the same thing is just as likely this time around. Apple likely won't do a traditional dual socket CPU-GPU set up either. Apple wasn't slavishly copying Dell/Lenevo/HP at the top end before and likely not starting in 2023 either.
Maximum wall power consumption than those other guys isn't the primary metric they are measuring themselves against. It was a relatively high performance threshold , but there wasn't really an "money is no object, maximum R&D spend" to be highest possible anywhere performance.
Apple probably is not building a system to win any "biggest" bragging rights contest.
AMD didn't cover the 4090 with the 7900XTX or XT and yet probably going to win the race over next 12 months of generating the most profits. (and perhaps unit sales in that upper class). Similarly, Apple is likely to put more focus on doing value add in the $6-28K than on the $28-50K range Mac Pro line up. That upper range really doesn't generate the kinds of volumes that Apple generally prefers to deal with. Same reason they generally don't like > $1,000 software packages either.