Any idea when there will be books that take place after the destruction of Romulus in the prime universe?
Probably not for a few years. We are slowly getting to that point, but have over three 'in universe' years to go.
After the cancellation of the nuTrek novels in 2010, I'm not sure Pocket are allowed to feature events from JJ Abrams' Star Trek. I hope I'm wrong and we get an epic novelverse Countdown equivalent soon! (perhaps that countdown begins after The Fall?)
It took place in the prime universe. It was shown on screen. It's therefore cannon. So the authors, while not allowed to play in the alternate universe, cannot ignore this in the prime universe as they have to remain consistent with cannon.
Legal departments don't care about in-universe timelines. To them, the Romulus-destroying supernova's a concept from JJ Abrams' movie, and so it may be off limits.
With the proviso that this is all speculative: It could, hypothetically, be off-limits to the novels if the novels didn't have the license for that particular part of the franchise. The Star Trek license is not automatically one big thing that encompasses the whole shebang. There have been times in the past where a tie-in publisher has had the license to only certain aspects of the Trek universe. For instance, Marvel in 1980-82 only had the license to ST:TMP and wasn't allowed to feature elements specific to TOS (although they managed to slip a number of references past the radar). Later, Malibu got the DS9 comics license instead of DC, so they could do DS9 and DC couldn't (though the two companies collaborated on a crossover). And currently IDW only has TOS and TNG (and Abramsverse) licenses so they can't do a DS9, VGR, or ENT comic (though they have slipped in references or characters from those on occasion). Again, though, I'm only speaking hypothetically. Clearly S&S's young adult imprint has a license to do the Abramsverse Academy novels, so...
So there's no evidence that Pocket can't write a Hobus novel, and at least one piece of evidence that they can.
I'm sure the fact that Orci co-developed the storyline to Countdown helped out IDW in that regard. As for novels, the destruction of Romulus will have to be acknowledged when they get to 2387, even if it is just some off-hand reference to "the recent destruction of Romulus." In fact, that could very well be the most the opic will be covered.
The Powers That Be may well want to avoid contradicting the various tie-in comics and instead focus on the scene away from the events directly depicted. The evacuation of Vulcan, chaos elsewhere in Romulan space, and like affairs may be shown.
I suppose there could always be a DTI novel that references the fact that in an alternate timeline Romulus was destroyed.
My fear is that once that date is reached, they'll have to stop publishing Trek books entirely as that timeline will no longer exist.
I cannot remember an evacuation of Vulcan in the tie-in material? Really all that needs to be mentioned is that the planet went boom! The reasons why can stay unknown.
If that happened, that would totally spoil Star Trek. I'm sorry, but it happened in the prime universe. Not some alternate universe. So the books should be depicting the destruction of Romulus. While Pocket's main Trek line is not allowed to play in the alternate universe, this is not an event that took place in some alternate universe. The books don't have to pander to Countdown. But Romulus getting destroyed is something that has to happen.