It sounds to me like you are discussing part of the SG15 brief.
I guess I was too subtle (lol). I'll say it plainly: stakeholders can charter a new Working Group under SC22. A sibling of WG21, not a study group inside it. The sole product is a second library standard for C++, with its own charter, its own convener, and its own tradeoffs on delivery and ABI.
It sounds like the previous effort was competing for WG21's plenary time, which is its own obstacle. That is evidence the committee is
a
suboptimal venue, not that the demand
c
an't be serv
ed. And the delivery problem you describe is solved the same way WG21 solves it: by specifying rather than shipping.
Nobody has done this because std:: absorbs the demand. Remove the subsidized supplier and the formation pressure becomes real.
Well, that's my theory anyway :)
Best