The Mac Pro line has been sold continuously since 2006, and Apple made a point of ending the Studio launch event by telling people that a new Mac Pro is coming. Why do that if not to reassure those waiting for an ASi Mac Pro?
There is a huge gap between 'reassuring' someone and 'leading them on'. Leading someone has a connotation that you are not really serious and just messing with them. It is more so a manipulation.
The reassuring aspect here was twofold that were both the opposite of 'manipulation' . First, it is a clarification that although Apple made some comparisons to the Mac Pro that this Studio was a replacement for the iMac 27" (both regular and likely iMac Pro also although the latter had long since been discontinued. ). Apple really did want folks to drop $1,600+ on completing the system and buy both. If Apple didn't say they were also working on a Mac Pro also a huge faction would have interpreted the Mac Pro comparisons as if the Mac Studio was the only Mac Pro 'transition' replacement.
All of that first point is really at its heart all about the iMac 27" replacement. That is really not about the Mac Pro at all. Apple said nothing about the Mac Pro before or after this iMac 27" replacement session. That session was really primarily about the iMac (and a move to some more discrete monitor solutions to cover that space).
Second, it is reassuring that the Ultra (which sounds like the top of the line up Pro , Max , Ultra ... somewhat indicative that they are out of 'bigger scope' adjectives) wasn't the biggest . How it is bigger... 'highest I/O bandwidth'. 'highest core count' , 'highest RAM capacity' , but something bigger with Mac Pro. [ No didn't promise an Nvidia x090 killer. Or a Threadripper 'killer' or anything specific like that. Just reassuring there were some compromises with stuffing the Ultra into the Studio's physical constraints. Bigger than a Mini, but not by a very large margin. ]
It was going to be as obvious as a turd in punchbowl that there was still an Intel system left in the line up that hadn't been touched at all by Apple Silicon. By doing all of the others they had painted themselves into a corner. They had to say something. And by saying they would talk about the Mac Pro 'later' gave them a huge 'get out of jail free' card to slide the Mac Pro substantive past the approaching 'about two year' deadline of WWDC 2022.
Did Apple get up and do more reassurances at 2022 about the Mac Pro? No. Again pretty hard to 'lead one on' when saying nothing. If Apple had got up at WWDC 2022 and say "Mac Pro even later than this'. That would be leading folks on. They keep throwing direct or indirect references to it. They are doing none of that. Hidden driver references to unreleased GPUs? Nope. Embedded resources to "Mac Pro 2022" in some help file? Nope.
If there was manipulation here it was in the misdirection here that the Mac Pro was the only Mac left to transition. Technically, not really true since there was an Intel Mini still sitting there plain as day in the line up. That tag line at the end was exactly placed to get tech press and tech gossip folks to regugitate that line. Everything but the Mac Pro is done. Repeat that over and over again to watchers and ta-da few notice that the Mini is left incomplete (and will drag on into 2023 along with the Mac Pro). That is leading folks on to what they wanted folks to look at.
Apple's SOP is to avoid comment. For them to say anything implies a deliberate choice. The only time I can remember Apple breaking their strict "we don't comment on unreleased products" policy was pre-announcing the Mac Pro 7,1, in 2017.
First, As pointed out above they had pragmatically painted themselves into a corner by saying they were done with everything else. It was as much 'deliberate' as 'necessary' due to the context.
Second, they didn't really substantively pre-announce the 7,1 in 2017. They mentioned some really broad brush stuff, but one again they had painted themselves into a corner. The Mac Pro was coming up on 2000 days without an update. It was an explicit, very illustrative milestone of just how deeply Rip van Winkle Apple had gone on product management for the Mac Pro. It was far more than that but even more uncharacteristic of Apple policy they actually cut/adjusted the price of the Mac Pro. ( technically they shifted existing core counts down to lower prices points. The point being it was so old that the 2013 prices they were charging is basically ridiculous even to them. ). And again it was the introduction of another Mac that was partially driving that. Apple had bet on the iMac Pro ( which was equally implicitly pre-announced there in that session. That session was in no way shape or form solely about the future Mac Pro . People spin it as if it was, but it was not. grading of MP 2013 effort (talked 'at' the existing product with quite vague 'read between the lines' to anything new). What 'pro' market was. iMac and aspects of 'iMac Pro' . )
Once again they were making a clarifying comments there to keep folks from later proclaiming that the iMac Pro was the Mac Pro replacement. [ In part, it was for the MP 2013, but the folks who didn't like the MP 2013 , the iMac Pro was 'even worse'. ] Without, the upcoming iMac Pro would they have talked about it? Probably not.
In both cases, I suspect Apple really didn't have hard fixed dates as to when they were going to deliver a Mac Pro or what the final set of features were commtted to. So not really pre-announcing something that doesn't even have finished specification document for. ( I think they were/are closer in 2022 to final specs than they were in 2017. Unlikely, it going to be 2024 before see anything. Especially it simply reuse the same physical case, power supply, and fans. )
And if they had intended the Studio Ultra to take the place of the Mac Pro, they could have said as much, either at the launch event, or leaked out via favoured journalists since then.
That was largely the whole point of mentioning the Mac Pro ... to drive home the point that the Studio was the replace for what Apple overtly said it was the replacement for; the iMac 27". Even though Apple said that explicitly ... some folks were going to screw that up.
https://www.apple.com/mac-studio/ ( from current Mac Studio marketing sales pitch page)
Some folks are going to 'read' that chart as if it is replacing not the system mentioned at the bottom ( as typical Apple marketing performance charts do by convention) , but has replacing all the Intel systems mentioned. As opposed to "iMac 27" replacement enters new performance zone". The chart is trying to show how up the ladder the Studio climbed. Mac Pro is more so there just to measure the steps on the ladder; not as a complete replacement.
The chart is also using the current price point of the Mac Pro 16 core to sell the Ultra Studio as a 'value bargin'. ( $7,999+ 16 core performance is now $3,999 .. what a bargain. Mac Pro is there to make the $3,999-4,999 look more affordable. Indirect that will reduce the sales of Mac Pro for those more constrained on budget whose workload fits and already have a suitable monitor. In part, though this is also because they discontinued the iMac Pro. That would have been a more coherent ladder replacement market for the iMac 27" Intel models. )