Thanks for pointing me to that Razer laptop (link)--I hadn't seen it and it didn't come up in any searches, but I guess that means that UHS-III is not entirely vaporware, and there must be a controller for it if Razer is using it.There was a Razer laptop with UHS-III for some reason. But otherwise it looks completely dead.
Also I posted an article on SD Express, but basically the word on the street is that SD Express is dead on arrival because no camera maker has signed onto the standard. They might adopt it eventually, but most new bleeding edge cameras are using CFexpress. So now the problem is, put a separate card form factor (CFx) and piss off people using SD, put SDx and no one has cameras with it and it downgrades UHS-II to UHS-I, or put UHS-II and people complain about no future proofing like he is in this article. No win situation.
Otherwise, though, it's exactly as you say--essentially a no-win situation. I guess if a controller exists they could have done what that Razer did and put in the UHS-III slot just as hypothetical future proofing for a probably-DOA-standard just to make people not complain, but I suspect they'd just switch to complaining about the lack of a SD Express slot anyway, so it would be whatever the cost for an exotic controller is for nothing.
Also of note: If SD Express (or UHS-III) ever does end up being a more widespread pro standard in 2-3 years, the sort of people who will actually buy pro cameras and $1/GB cards are also the kind of people who will probably have upgraded their pro work laptop by then anyway.