Maybe not, All the art and graphic design of the game (including the cinematics) imply that these 5 companions are the main ones in the story.
Just because these are the "main" (aka tadpoled; aka Origin) companions doesn't mean there won't be more very soon.
We might get another 1-2 tadpoled companions; the rest are likely to not have tadpoles, and to show up later in the story (say towards the end of Act 1, since the party gets fixed after that).
One last thing. Can someone confirm whether or not Gale is actually tadpoled? I haven't seen anything yet to confirm that he is. Then again, I've been mucking around in the early game to try different things out.
