I'll be more than impressed if we have 2 alts as unlockables along side everyone's default. That's impressive that they are giving us that many options without having to pay extra for it imo. I only expected one alt for everyone but from recent gameplay it looks like everyone will have 2, which is amazing. Then buttloads of DLC skins if people still aren't satisfied.
Well the current theory I've seen floating around is that there is the default & 1 alt that we've seen in the story trailers so it's safe to assume they are in the game, then on top of that in the videos detailing Star Labs they seem to have yet another different alt.
So one default + 1 definite alt + 1 probable Star Labs alt (possibly unlocked by doing all the Star Labs missions for that character.)
I mean technically we don't know but this is extremely likely.