Perhaps some bug fixes, like the fuzzy mane being fixed. And maybe some more stuff, like manes, tufts, eyes, et cetera. Even maps, if possible.
Also, maybe the movie maker could be finished. I'm not sure how but it'd be interesting.
An unlikely thing I still want would be more marking space for custom markings, but that's probably just me.
A larger variety of things to type in the chatbox, possibly with a feature to copy and paste. (Although I can see why it wouldn't be the best for that last option...?)
I dunno. I like how plain and simple the game remains, as it should be, but an update sure would be nice even if the creator of the game is no longer present. That's just what I think.