Celestial will get jelly ad assassinate her because she did a better job.
SO DOES THIS MEAN SHE MIGHT LOSE HER ALICORN POWERS?
it could mean a couple things or nothing at all.
on one hand, it could mean that she isn't a full-fledge long-lifespan alicorn like Celestia and Luna (i like this idea best), that she might very well revert back to unicorn (unlikely), or that we're going to have a mane six alicorn party (very unlikely)
on the other, they're never going to actually discuss the mortality of the main characters in the show, so unless one of the above happen it's really just a reassurance answer for fans