It seems that nobody here has yet discussed the November 2021 report recommending the future of space telescopes after JWST.

https://www.thespacereview.com/article/4292/1

In brief, the recommendation takes the mission concepts of LUVOIR (like JWST but bigger and choosing, like Hubble, UV through IR wavelengths rather than just IR) and HabEx (a telescope that would image nearby terrestrial exoplanets) and merges them into one space telescope not quite as big as LUVOIR would have been but larger than HabEx would have been. Its role would be to provide new capabilities for imaging and studying exoplanets, while also having solid capabilities for various cosmological studies.

In addition, the recommendation is for two equal secondary-priority space telescopes, one observing in xrays and one in IR.

It seems like all three of these, if developed and launched, would be aiming for about the 2040s for start of mission.

The report is interesting in suggesting LUVOIR would take until the 2050s to fly based on the experience with JWST. Would be nice to figure out ways to speed things up. Here's a quick summary of some other cutting edge things I've been following recently and over the decades. Some of these seem to be good study topics.

Space Interferometry Mission (SIM), Terrestrial Planet Finder (TPF), and Planet Imager (PI). There is a new evolution of planning at least with the SIM. The Planet Imager discussion is more elusive with a flying formation of interferometers 1000s of kilometers apart to image extra-solar planets with enough resolution to see continents and oceans. This concept has mostly been studied 20+ years ago.

Solar Gravitational Lens (SGL) mission to use the sun as a gravitational lens. Clever strategies can build up images that resolve extra solar planets.

NASA is also now studying the ORCAS mission that uses a space-based laser as a guide star to help ground-based telescopes improve their adaptive optics resolution. I've been personally involved in some of these discussions.

Solar Gravitational Lens telescopes are such a great potential, but are certain not to be in operation within the next few decades. Probably at some point there'll be dedicated SGLs sent out to survey different multiplanetary systems – TRAPPIST-1, Alpha Centauri, Proxima Centauri, Tau Ceti, etc., where one telescope could survey multiple planets. But simply getting out to that distance, several times Voyager 1's current distance, seems like a not-in-our-lifetime requirement.