The internals and part of the chassis had to be completely reworked, and they had to fit inside a specific enclosure which in many ways would be harder, so I wouldn’t be surprised if the studio and iMac Pro cost about the same in RnD. The studio just uses a “reworked” design from the Mac mini and isn’t that complex.
I think they are comparable in many ways, but again I’m not necessarily saying they’re going to discontinue the studio. That being said, just how the iMac Pro was a stop filler, the same could be said about the Mac Studio. We just don’t know.
Personally I bought a Mac Studio myself and love it, and hope that it stays around for a long time. If I upgrade in 3 years, I hope there are new studios to upgrade to.
All I’m saying is I wouldn’t be quite so confident. Apple has done many odd things with products that are in niche categories.