Celestia and Luna will die, Sunset Shimmer and Trixie will replace them as the new sun and moon alicorns.

[M. A. Larson laughs in the distance]

I assume it's just a joke. Seeing as the rest are kind of a… given…

Might as well say "There will be ponies in it."

Though, implying that episodes will focus on characters other than the mane-6 is rather promising, as those are too few and far between.