Larian made verticality one of the main marketing points, so they need to deliver.
Maybe you've got a false advertising lawsuit on your hands
If we do get flight it's probably going to be a pretty simple implementation which is going to boil down to the same effects provided by giving flying creatures bigger jumps. Honestly, the bird jumping around does look a little silly and I'd like to see a simple flight system in place of that. Though anyone expecting more than a hover system is just setting themselves up for disappointment.