I hope all animals in PZ1 are in PZ2 either in base or very early on, so that the roster can really expand.
Still so many animals that could have been in PZ1 - Walrus, Echidna, Secretary Bird, Tree Kangaroo, Coati, Shoe Bill, Musk Ox, Generuk, Rabbit/Hare, Mara, Howler Monkey, Chameleon, Cobra, any Duck, Pelican, Spoonbill, Ibis, Goose, Puffin, Rhea, Numbat, Bilby, Lyrebird, Ribbon Seal, Sika Deer, Blackbuck, Kudu.
Then Aquatics, and Flying animals too.(thus tanks and aviaries.) So many new choices available. I really hope the final number of animals is a lot more than PZ1. Happy to have more expensive expansions with many more animals also in addition to DLC to ensure more animals/flora/features. But really want any PZ1 animals in very early.
More customization/interaction of the small exhibit animals & exhibits would be great and increase the fun of using these animals and designing for them. Same for walk though exhibits. That would make more animal options again.
Other features:
Better pathing options.
More barrier types and more varied basic shelters.
Much better performance on PC with less lag with more animals for as long as possible.
The features that were added throughout PZ: Koala/Kangaroo baby's from pouches, brachiation, diving, population management from the get go, restaurants, gift shops,
New features like: egg laying/ nesting/ hatching, interactive cinemas, more animal interactions
More tycoon features.