Gale isn't evil. You have to succeed persuasion check or he leaves if you go with evil route in act 1. He's angry at us. So then you're stuck with Shadowheart, Lae'zel and Astarion, that is... if they are even alive. If not, well then... you have only generic mercenaries from Withers.
If someone manages to lose all origin characters before the act 1 party, I don't think it's Larian's fault for having no content.
