With Apple computer sales plunging comparatively more than competitors, the Mac Studio is in some ways in competition with Mac Mini.
So contrary to Gurman's assertion it may make more sense to have a common platform of either Mac studio or Mac mini, but not both. That makes production cheaper, and where personally having both I prefer the Mac mini, as it can be used as plug in servers, and fulfils most of the needs for most users.
I would not put too much weight into the drop in Mac sales. The entire PC industry took a beating and while yes, Apple took more of a beating, Apple also saw stronger sales the previous span of quarters than the rest of the industry's OEMs. So Apple was able to better meet the surge in demand than the PC OEMs (Apple was not as constrained by parts shortages, for example) and therefore they have sated said demand fully whereas PC OEMs still have some trailing demand they can fill.
The significant majority (over 80%) of Mac sales are portables so it is not surprising that Apple desktop models are on longer refresh cycles than the portables are. Hence the iMac and (likely) Mac Studio skipping the M2 generation of SoCs (and if Mac Pro had shipped with an "M1 Extreme" as planned, it likely would have skipped M2, as well). Mac mini was refreshed with M2 because Apple saw demand for a "pro" model with a more powerful SoC option and more expandability and M2 Pro was ready so it was easier to just release it with M2 instead of M1. But I would not at all be surprised if Mac mini skips M3 (at least the "pro" model).
So Mac Studio still has an important place in the line-up and will continue to be upgraded going forward, IMO, even once Mac Pro arrives to anchor the top-end of the line.
Of course if they make the decision to drop the Studio, then they can change the form of the Mac mini, but then know it will be the common hardware platform and can make that available in multiple configurations with very little production overhead.
With the best of both Mac Mini and Mac Studio into one unit with heat sink considerations being less of a problem in the M3, the variations would still be there without significant extra cost, so it would appeal to first user and high end users alike, based on the respective configuration.
With a common platform but much greater performance variations within it, makes more sense than two separate products competing against each other.
As Apple has noted in the past, Mac mini is in many ways a "catch-all" product that fits the market niches no other Apple desktop can. It's dimensions are important for many applications (data centers, HTPCs, etc.) and making it significantly larger to accommodate Max and Ultra class SoCs and (OEM) expandable storage modules would impact those markets. It would also raise the base price of the unit (Apple will charge more for a platform with more optional capability), which would impact it's desirability for niches where the current base model (which actually went down in price) is sufficient to task.
So Apple and its customers, IMO, are better served with the mini and the Studio existing.
Tim Cook flapped his gums about another intel based mac pro.. That was 3 years ago.
That is still a possibility even though we tend to think no more Intel macs (as) its recognizing businesses require several years of software support.
I think if Apple was serious about updating the Intel Mac Pro, they would have done so last year when Intel announced the W-3300 Ice Lake series of Xeons. We did have rumors to that effect at the time
and the CPUs did appear in the Xcode 13 beta.