The M1 costs Apple relatively little to produce per unit - I would expect them to keep the overall design for a Mac Pro but have stacked modules such that the side wall of the Mac Pro is a grid of 4 or more such modules each with co-located memory like the M1 has. Obviously performance would depend upon the application being amenable to a design like that but a 32 or 64 5nm core Mac Pro is not out of the question, and would be impossible to match for performance in the next few years by any Hackintosh.
Even after capacity frees up at TSMC for AMD to move to 5nm, they won’t be able to co-locate memory like the M1 does due to standards compliance with DRAM sticks.
I think the next couple of years will be really turbulent for other vendors - the M1 is likely far more significant for the PC market due to how disruptive it is than it is for the Mac market.