I think the best balance would be to have 100% of the MSQ be soloable; including the ability to skip running the CT raids and only watching the cutscenes if you want. ANYTHING and EVERYTHING not directly tied to the MSQ should be multiplayer and completely optional for the player. If they want to go through EW by their lonesome and then start dipping their toes into multiplayer, let them...and make them start at Sashtasha and unlock everything per normal.

The game will only benefit from including the fairly significant solo-gamer crowd provided the non-MSQ stuff isn't impacted. Well, perhaps adding trusts/duty somethingorother NPCs to everything. I wonder how frequently we'd end up at level 90 running Toto-Rak if folks could do it with trusts...