On the brighter side (or what little of one there is) of the current game's lack of South American species, I can't help but think about how hard a South American pack (or packs) would go for a sequel when introducing flying and fully aquatic species.
The Amazon alone could probably have two-three packs without running out of popular animals, it's loaded with terrestrial, aquatic, and flying species that are common in zoos, from the canopy to the river, combining all three types of animals in one ecosystem so easily. I'm especially thinking about those Amazonian tanks that are so common in zoos and as a prime freshwater exhibit in aquariums—Arapaima, redtail catfish, piranhas, manatees, etc. All of that in combo with macaws, harpy eagles, conures, and all of the more land-based species that could've made it to the first game - ibises, spoonbills, agouti, tinamou, ocelots, and of course all of the monkey species we should've had. I dunno, maybe I just really want an Amazon river pack.
A bit rambly, but my point is, a lot of Amazon exhibits I see tend to combine aviaries, aquariums, and standard habitats in one complex, so I'd be thrilled to see a sequel venture into that territory if covering the region. : p