Depth (actually thickness is the word you’re looking for) was the same on 12 and 13 Mini as on the 6.1” equivalents. Therefore, if this imaginary phone did not have a camera bump it wouldn’t have the same thickness.
This leaves either using camera sensors/lenses which are generations behind (thus, it wouldn’t be a Pro), or making it very thick.
Even if a phone that thick is a marketable option (it isn’t), adding all the features to make it a Pro would lead to a severely compromised battery life.
As much as I loved my 12 Mini, I wouldn’t buy another, not because of the cost but because of painfully inadequate battery life.