I've always been curious, when the design phase ends and construction begins, wouldn't new technologies have emerged by then? Do they try to keep up and incorporate improvements or are new breakthroughs rare?
After 25 years in the making and now waiting to be launched, technology of course has advanced enough for JWST to be "obsolete" in that sense by the time it's operational. However, new space telescopes take so long to be operational but they still give us amazing data... even if what they give us is peanuts from old dusty tech it's still worth it. Anyways, JWST is going to be incredible... heck, even after so many years Hubble still produce a ridiculous amount of good data and research and it was designed in the 70s! Can you imagine if launching was cheap and we had a constant flow of budget for space telescopes and we could launch a new improvement every year (after an initial ramp-up of, say, 10 years)? Unfortunately launch costs and cadence has been a major blocker so far to the things you asked about IMHO.
Unfortunately the JWST isn't a visible light telescope — it's sensor is for infrared light [1]. It's not going to be providing images like Hubble did, as it was designed to look at extremely far away galaxies and nebulae that have very redshifted light.
The idea related to the OP is that JWST can actually image distant exoplanets without depending on spectrum and/or transit analysis like it's done today. In a way, JWST will be able to give us visuals of exoplanets we only dream about today, much like what Hubble did for some objects previously only imagined. At least that's how I understand what JWST can do for exoplanets hunting.
