A drow ranger summoning a big black panther ? Reminds me something... :p
Reference aside, I think all possible animal companions will be present in final game. Larian probably didnt have time to put them all in the EA...

I hope you're right, this request is actually more because I love my black cat in real life. So whenever myself or my girlfriend play as a Ranger we take a Panther in homage to our little guy.
I just don't connect with the other animals in that Role Playing sense. Though I'd love to see stuff like the Flying Snake, etc. too. Just for people who want different things.
I really feel the Boar was a letdown. =/ I dunno, just super limited, and it didn't have a stat block to compensate for it's charge ability being so niche.
I keep thinking a Panther would help Rogue/Ranger Multiclasses especially with sneak attacks, etc.