If, in D:OS2, all available companions are those 3 that escape prison with me, I'd be pretty disappointed.
In theory, there could be safe havens in the world where you can meet other sourcerers, but they would need to be designed to fit the plot (potential replacements wouldn't be hanging around public places like bars or libraries). I don't know how the Hall of Echoes is being implemented, though. If party members can be changed, whatever the reason you'll be able to enter and leave the HoE alive, it will need to be transferable or extendable. For example, you couldn't be specifically chosen by the gods, but you could acquire 4 talismans they created that only sourcerers can use, or something.
