If Apple keeps the same iMac chassis there is no way to physically fi t a Pro or Max variant in there. The RAM packages are more numerous and take more space. TSMC N3 is going to do nothing to make them smaller. The basic fundamental package size it too big to be 'stuffed' into the 'chin' of the iMac 24".
The iMac is going to 'beat up' the Mac Studio ..... probably not going to happen.
The rumors have outlined a 'plain' M3 in a iMac showing up in testing logs. That is it.