Good question, and it's the thing I've been working on most. Right now the approach already changes in a few ways: dangerous species tear nets, so you need the tranq gun and have to deal with them charging you; some species only show up at dawn, at night, or in certain weather; cliff dwellers (goral, lynx, golden eagle) need climbing gear and slow you down on the rock; and the Asia map cuts your gear effectiveness in half, with tracked hunts where you follow calls and prints instead of waiting. Bait is a lure, not a trap — it only lowers an animal's guard for a moment, so a jumpy species in open grassland plays very differently from a slow one in the reeds. Endangered species each have their own condition (a time window, a habitat, sometimes rescuing them from a poacher's snare).
What I'm adding next is more of that per-species and per-habitat: grandpa's camp will become a feeding site that draws certain habitat groups at dawn and dusk, and a sighting log that gives you the exact time/weather/zone conditions for a species' legendary variant. I'd also like flock and herd behavior (spooking one bird spooks the group) and species that react to your dog differently. So the long-term answer is yes — fewer new animals, more different ways to reach them.