They still earn tens of millions each year from all the TOS, TNG and other series' stuff. CBS wants to capitalize on it. The Abramsverse movies, especially the 2nd one, haven't made that much money in the end at all. So CBS wants to play it safe with the prime universe, a universe no one will be against they feel.
They earn tens of millions per year with little to no investment. They may swallow pretty hard when they see what it actually costs to keep up with shows like Game of Thrones and Walking Dead.
A space-show is going to be even more expensive than either of those, particularly to the quality of modern productions, which probably means they'll want to go with more of a sure bet.
That likely rules out a 25th century show, as audiences lost interest over time in DS9/VOY, so probably don't care about a continuation of any of those story lines.
Leaving them with the two most popular properties, TOS and TNG, so my guess is we'd get a reboot of one of those shows (probably TOS, since there seems to be more general interest in that era).