One of the unfortunate side-effects of X-Men: Days of Future Past being one of the most crowded movies of the franchise so far, in terms of the number of mutants included, was that some of them ended up with very little screen time, others were cut from the movie entirely, and one of them disappointingly departed from the rest of the movie after one truly brilliant scene.
Along with Cable, one of the mutants who was considered for X-Men: Days of Future Past was Jubilation Lee AKA Jubilee. The character has appeared in three of the X-Men movies so for, but aside from a deleted scene in X2 where she showed a glimpse of her powers, she's been restricted to brief cameos. Nonetheless, these appearances established her in the movie universe as being about the same age as Rogue, Pyro and Iceman.
It's unclear where Jubilee ended up in X-Men: Days of Future Past's darkest timeline, though the most likely explanation is that she was killed off by the Sentinels along with Beast. We can, however, get an idea of what Jubilee might have looked like in that timeline, thanks to costume illustrator Phillip Boutte Jr. sharing his costume concept art for the film's characters, including two different versions of Jubilee. Bishop, Blink and Iceman also had some pretty cool alternate costumes as well.