I think a more interesting dynamic is already in place. If you choose to do certain things in the game, you can lose Astarion. Other things, you can lose Wyll. I believe Shadowheart will disappear too if you make certain decsions.
This would force players to act in certain ways just to keep a preferred class in their party. If I really want a wizard in my group and there isn't a way to hire a mercenary for that role, then I'm basically forced to keep Gale happy. Or at least not mad enough to leave.
Maybe we'll be able to hire mercenaries after Act 1 to fill a needed slot in the party, like DoS. Until we know for sure, I'd like the option to keep any of these companions from leaving unless I do something really extreme. I don't want my actions forced in a certain direction just because I want a Wizard in the party.
