Until the last year or so I'd have been dead against this, but I think now (8 years after Apple tried to prematurely force a switch) USB-C is more established (and multi-port USB-C hubs of various types are finally available) I finally agree with you - especially on a desktop where any USB-C-to-A dongles you need are plug-once-and-forget.
USB-C is still a dumpster fire of invisible incompatibilities between visually identical ports and cables and mind-boggling naming conventions (USB-no-space-4 2.0 anybody?) but at least it's an industry standard dumpster fire.
Only concern is the horizontal USB-C sockets on the Mini which look a bit close together for plugging dongles - the vertical sockets on the Studio are better in that respect.
Personally, I prefer the Studio design, but I think that's extremely plausible - the M4 max has to be thermally suitable for the MacBook Pro so fitting it into a Mini chassis with more space for a quiet cooler shouldn't be rocket surgery.
In that case I think its more likely that the Studio Ultra would become the new Mac Pro in all but name (a worthy replacement for the trashcan) - the actual 2023 Mac Pro is really a niche product for people who need specialist I/O cards or massive internal NVMe storage. Currently, it offers much better PCIe bandwidth than an external TB-to-PCIe enclosure - although that may be eroded by Thunderbolt 5/USB4 2.0 (see above!).
Of course, we're assuming that the M4 is going to follow the same regular/pro/max/ultra/maybe-extreme progression. M3 has already upset that a bit, with the M3 Pro being a completely different die rather than a Max with the end chopped off, and no sign of ultrafusion on the M3 Max - and with the M3 Max being more powerful in relation to the pro than was the case with M1 and M2,