The problem with many vanilla animals is that they are stylized, something that wasn't welcomed by part of the community as we have voiced our dislike for many models since the release of the game because we want realistic looks, not stylization, and that has caused a clear change in the looks of DLC animals, however, this has left a big quality gap between DLCs and vanilla content that imo is just too noticeable.
And while I would love to see remasters of vanilla animals, they most likely will never happen officially, as from a financial standpoint (let's not forget Frontier doesn't stop being a company) it makes no sense to spend resources on assets that already are finished, even if their quality is inferior and the community complains about it, because people will keep playing the game even if the lion looks like a cartoon character.
Personally I would hope for at least some animation improvements on the vanilla animals, as the system they use allows for switching animations easily between different rigs, if only they could use the animations of the lechwe on the bongo and the nyala... One can dream.