If they're holding 1:1 years as it seems, then 1994 to today is 25 years - and 2002's Nemesis was the last time we saw an outing, 17 years ago. So the "fifteen years ago" thing is interesting, and offhand probably relates to the Hobus supernova and the destruction of Romulus (with mention of the rescue armada). But what happened after that? Gonna be interesting...
According to Memory Alpha, 2371 is when Generations takes place in 1994, and 2379 ties to 2002's Nemesis, where Shinzon tried to attack Earth and failed. Seventeen years after that would place the film at 2396, and 2381 for our ostensible "incident" mentioned in the trailer. Poking Memory Beta for the licensed works...
...oh god, the Destiny novels are in 2381.
Fudging that 15 years a bit (depending on what month/week/day it's stated, etc) according to Memory Beta:
"The Federation begins providing material and humanitarian aid to the devastated Romulan Star Empire, and attempts to facilitate negotiations for the re-establishment of permanent government." That's immediately post-Shinzon, and makes some sense.
Though, I suppose my thought above was wrong - at least, assuming they stick to the established timeline - since Hobus was 2387, eight years after Nemesis. We'll see what it's referring to, but that at least is a look back at the setting so far.