Many times Star Trek has taken us to the future only to reset the status quo at the end of the story arc. Tapestry (but in reverse?), that time Voyager crashed in the ice, and all that.
How likely is it that Discovery went to a mutable future, just one of many, especially with the Temporal Cold War, Carl, Q, Trelane, Janeway, the HMS Bounty, and any number of other temporally active agents out there in time? How locked in is the 32nd Century?
We know, but no Star Trek character which live before the burn know about it. The Discovery should go back in time for that, and it’ll always be too dangerous.