Let's assume a Mac Studio M5 would start at $1999, and that a M5 Max upgrade 128 GB would be about the 1000 it is now. Then an M5 Ultra 768 would be something like $1999 + 1000 + $4000 - cheaper than the current top of the line (which will never happen) so I'd presume about the same $10,000.

Or they could finally make the Mac Pro respectable and have it two M5 Ultra Mac Studios stuck together (or give it NUMA RAM: on chip + expandable).