A South/Latin American animal pack's only plausible ungulates would be a peccary or pudu--both of which I'd like to see (since PZ's SA representation is so lackluster outside of the number of exhibit animals), preferably the Chacoan peccary and southern pudu. A more general rainforest pack (which, to be clear, is something I wouldn't really want, since it lessens the likelihood of a more focused return to South America, much less more fleshed-out African/Asian rainforest animals) could bring the red river hog, and the speculated Asia pack has obvious candidates like the Przewalski's horse, takin, and markhor, as well as possibilities like a muntjac, Pere David's deer, or musk deer. My personal top 10 ungulates I'd like to see, in no particular order:
1. Chacoan peccary
2. Red river hog
3. Przewalski's horse
4. Sichuan takin
5. Markhor
6. Roosevelt elk
7. Siberian musk deer
8. Chinese muntjac
9. Blackbuck
10. Nilgai