Considering a Mac mini with an M1, 16GB of RAM and 512GB SSD is $1099, $1499 might get you the 10C/14G M1 Pro (with the 8C/14G being $1399 and the 10C/16G being $1599). If you want 32GB of RAM on top of that, well now you are at $1699-1999 and you would, IMO, be extremely foolish not to go with the $1999 Mac Studio at that point considering how much more performance you get for literally little to no extra money.
It's difficult to see why Apple would want introduce a top SKU intel Mini replacement with the Mac Studio firmly in place. Right now, the people who can afford $2k must surely be buying one - Apple must surely be waiting for at least WWDC to make sure that initial demand isn't stymied by the arrival of a cheaper option.
Price-wise, is there really enough room for an M1 Pro mini? $1099 gets you M1 with 16Gb RAM and 512Gb SSD, another $400 would upgrade you to the same 32Gb as the M1 Max Studio (if that were possible) and this leaves $500 in the budget to get you from M1 to M1 Max.
In a 14" MacBook Pro $500 gets you from M1 Pro (8c CPU, 14c GPU) to the same M1 Max in the Mac Studio - (10c CPU, 24c GPU).
If Apple did put an M1 Pro in the existing Mini - whether or not the redesign it to fix wifi/bluetooth - it immediately makes the M1 Studio look the better deal. Price wise, we're taking about potentially a $100-200 uplift to upgrade the M1 to M1 Pro - a situation that doesn't exist anywhere in the Apple range.
The closest analogue here is upgrading from M1 MacBook Pro 13" to M1 Pro MacBook Pro 14". But to match up specs between the 13" and 14" you're specifying 16Gb RAM and 512Gb SSD which comes to $1699 in the 13" model, but you can pick up a 14" for $1999.
So let's just say that a Mac mini M1 Pro 16Gb RAM, 512Gb SSD would retail for $1299. This is $200 more than a similarly upgraded base M1 model. Add a 32Gb RAM expansion (if Apple offer it, for $400) and you are at the magic $1699. anyone with a bit more budget should upgrade to the Mac Studio and get a 'cheaper' M1 Max CPU.
What does this do for Apple? I think this would bring the average selling price of the Mac mini up by a serious amount - a nice little earner, with a potential for a dent in Mac Studio base model sales. With the advent of the Studio Display Apple must be thinking that people who buy a decent headless machine will want to add a matching monitor which again brings more profit to Apple coffers.
Portwise, what would an M1 Pro mini get? Let's look at the 14" MacBook Pro - I think 3 Thunderbolt 4 ports, a USB-A, HDMI 2.0, port would be fine. It makes me think that the connectivity in the 14" MBP is limiting for those folks who choose M1 Max since it appears to be capable of driving 4 Thunderbolt ports and 2 USB-C 10Mbps as well as a couple of USB-A.
If Apple choose to offer an M1 SKU in the same case they could follow the same theme - turn one of the TB4 ports into USB-C - and this means Apple don't have to offer different case SKUs with cutouts. It could especially be the case if - as with the Mac Studio - Apple put one TB/USB-C port on the front of a redesigned case. If they want to they could offer 2 USB-A ports (for keyboard and mouse) rather than the one offered on the MacBook Pro 14".
Final question now - could Apple actually just keep using the existing 'classic' case? It would certainly draw more people towards the Studio for aesthetic reasons. There's room at the back for the third Thunderbolt (or USB-C) port if they wanted to maximise profit by not spending the money on an engineering redesign to fix the wifi/bluetooth.