I've mentioned it before, and no, we're unlikely to see reptile characters.
First, plain and simple, I don't like them. Not the animals themselves, I have nothing against turtles and snakes and such. I just don't think they make very appealing anthropomorphic characters.
I tend to consider the characters more "people with tails", than "animals standing upright". As such, while it's pretty easy to anthropomorphize a fox or a rabbit or a bear, when you start getting into the stranger animals like turtles, snakes and iguanas, there starts being more of a disconnect- it gets harder to engage the ol' suspension of disbelief.
Ditto birds- it's easy to picture a fox paw slightly morphed into a functional hand- much less so to picture a wing similarly converted. Yes, I know most artists will draw the feathers as acting like fingers, but that's like trying to hold a handgun with a feather duster.
And second, with minimal exceptions, I'm about done adding new characters for a while. We have plenty already, including quite a few that have been around for years and have yet to have any real screen time. (Gino, for example; Duncan first appeared eight years ago and has been in a grand total of four panels so far [that's panels, not strips] plus Packrat and Sarge, and newcomers Ambush and Upshot, we haven't seen Anthony the Tiger since... what, 2010... And so on.)
I need to spend more time exploring the guys and gals we've got, before we go adding any more.