Well of course its not going to be simple, and I doubt it would even be possible for the JWST successor, which I assume are already being sketched out, but its

Well of course its not going to be simple, and I doubt it would even be possible for the JWST successor, which I assume are already being sketched out, but its an interesting idea to think about. Satellite swarms are a very active area of research, along with cheap launches enabling cheap hardware based on substantially COTS electronics, which means 10 "unreliable" things, of which 9 may fail may be cheaper than 1 gold-plated one that will definitely not fail. And yes, they have small elements, that's the whole point. A small element is disproportionately easier to produce than a bigger one. The point of The Swarm would be to offset the small area individually small elements with a large number of them. ALMA does this, and they even pick the dishes up with giant forklifts and move them around to reconfigure the array. Optical interferometric arrays are very hard and only recently even possible, so it's unlikely you could do it in space "soon" (even LISA is still a long way out, and that's been planned since I was at school). I obviously don't have a handle on if the added noise from positioning errors outweighs the literally astronomical baseline advantage. And yes, Hubble might have lasted 30 years, but JWST has about 10 years life, and then it's dead and will fall away from L2 unless they can get a refuel/regas mission launched (it does have the ports for it) to it in time. Of course any number of practical issues can torpedo such a thing from the phase space of feasible implementations, but they're still fun to think about.