You mean that you might actually have to pick and choose which ROLES you want your party to PLAY and not be able to cover all the classes fully? *gasp* How terrible! (/sarcasm)
It's totally fine if you can't use all the skill trees at once. It's not a bad thing at all to have to pick and choose which areas to focus on. That's a large part of building a balanced team.
Zero chance Larian will bump the party size to 6.
(Also a Ranger/Scoundrel seems like a poor fit because Scoundrel skills require a dagger and Ranger skills require a bow, and switching between the two is usually a poor use of AP.)
