Correct. Not a “hard” problem at all assuming the SoC is Mac specific. Which it will be. There is not going to be any iPad Pro logic board sharing for the production machines. It will be USB4, that’s my bet. 2 of them in the MBA and 4 on the MBP. We’ll find out in about 12 minutes!
Is it Mac specific ?
The Mini and MBP 13" just dropped in the number of supported external monitors. ( can only drive two display like an iPad)
MBP 13" is limited to two ports. (not enough output on SoC to drive two TB controllers )
No 10GbE on the Mini. ( apparently not enough output on SoC to drive a 10GbE controller )
The RAM is integrated into the SoC. ( trying to save space in Mac where no where near iPad Pro like logic board contraints ).
If this turns out to be the same size package as the A14X in the next iPad Pro ....... there is decent chance this is a labeling thing than something specific for the Mac. There really isn't a reason to go backwards on graphics output support and I/O on a Mac is doing something specifically for a Mac.
It does have Mac stuff on the SoC that the iPad Pro probably won't use. But this doesn't appear to be something that is a clearly a large break from the A-series.