What would it take to get such a thing in orbit? Are there any
*knowledgeable* readers left in sci.space.policy that can comment on
this (Fred, Jeff and Greg excluded)?

In my un-humble opinion this is the most important laboratory for long
term crewed space missions that NASA could orbit. In fact, if we are
wasting money on SLS anyway, let's make this its VERY FIRST payload. It
would never "pay for itself" because it could be done far more cheaply
with existing boosters, but if the money is being stuffed down a hole
anyway, why not? And it doesn't need an upper-stage capable of TLI
unlike the so-called Deep Space Gateway. In fact that would be totally
counterproductive. You'd want easy access to this from (soon to be)
existing LEO transports for a variety of reasons.

Nor does it *have* to be a NASA project. But NASA would be the ideal
supervisory agency since they have the ability to bang heads together to
get the various aerospace contractors to co-operate rather than compete.

But this presupposes NASA stops competing against US industry for launch
infrastructure....

Dave