What happened to the Klingons,
Someone should ask the Orions, since they used to buddies in the 23rd century. Or the Federation, sicne they were allies in the 24th and it was projected that the Klingons were a part of the Federation by the 26th century.
What happened between Cardassia and Bajor?
I suppose… really good, if Rallik is anything to go by. The Cardassians are still around, at least. Maybe someone from Discovery should catch up with them, since the Federation was familiar with them in the 23rd century in both the prime timeline and the Kelvin timeline.
What are the Ferengi like now?
Beats me. No one bothered to talk to the Ferengi seen in S4.
Are any descendents of characters we know around?
How often do we see the descendants of characters over a hundred years removed in these shows?
The last one likely got blown up in The Burn. They probably haven’t built a new one yet.
Well, is the Dax symbiont still around to begin with? Even if the symbionts live for a thousand years, a lot can still happen in a thousand years.
Who lost the Temporal Cold War and what was the punishment?
Clearly not the Federation and the Vulcans/Ni’Varans as they are still around. Thanks Archer!
Time travel is banned. We know that from S3. Wonder how the Krenim are taking it, since time travel was their thing?
The map of the Alpha Quadrant in Admiral Clancy's office places Cardassia and Bajor within Federation borders. Though it gets odd, since there apparently is still a DMZ around Cardassia, which there shouldn't be if Cardassia were a Federation member. Then again, you'd think the DMZ would have been disbanded once the Dominion War started.
It was never revealed which member worlds were threatening to leave the Federation if they helped the Romulans evacuate from the impending supernova.
Maybe Cardassia was one of them, and it renewed hostilities to the point that the DMZ was re-established.