Heck, take Big Finish’s approach to the Doctor Who universe and apply that to Trek — i.e. find pretty much any excuse for endless new spinoff lines or box sets! You, I, and probably everyone reading this can endlessly come up with Trek-series ideas, especially in an audio format that doesn’t have to worry about visual-effects/setbuilding budgets.
So anything from obvious ones like a 2nd-5YM-after-TMP series (and/or a 3rd-5YM-after-TFF one) — mostly with soundalike actors, obviously— to stuff that’s more in the “only fans would get this” category that would never happen on TV because general audiences wouldn’t know/remember anything about them (say, a post-DS9 series about seeking out the rest of the lost Changeling orphans to vaccinate them before the S31 virus reaches them), to “further adventures of that character from that one episode” stuff (Helen Noel Investigates!), to in-depth series about a given planet (Vulcan? Babel? etc).