I'm skeptical about otterbears for To'resk and Dras mounts. They were introduced as cool-climate animals. Trison and oliphants are also cool-climate animals. We have not seen much in the way of subtropical and tropical animals or plants because the current fauna were focused on cold and temperate climates. This is because they originated as kickstarter teasers. Northern climates are much more familiar to prospective players and backers, hence more appealing, than subtropical and tropical climates.
I expect new animals for warmer climates. SBS has long ago hinted strongly at reptilian forms for swamps, so I expect crocodilians and large snakes to be in the picture. I also expect the feature animals to be combinations of terrestrial forms, just as several other feature animals are, including otterbears.
For mammalian types, I expect some forms based at least partly on water buffaloes and hippopotami. These would make a little more sense as mounts than carnivorous reptiles do. Although the appeal of carnivorous war mounts is quite obvious, it would not be rational for noncombatants to risk becoming lunch for their transportation media.