You ought to know how invested in the power struggle your players are. There is an important nuance that would drastically change what would be advisable:
- PCs wish to remain bystanders of the conflict. They are certain they will adapt and get by whatever happens.
- PCs hope that things will turn out OK (ie. not a demon overlord), but are not willing to really take sides or risk their lives.
The trick I use to "balance" things out and bring back players to being actors of the conflict : thwart their expectations.
For option #1: PCs probably have some plans for themselves. « Let's cut ourselves from the world, or start out some secret society that will enable us to survive and thrive ».
What could you do? Well, let them make plan, build their stronghold/secret hideout/recruit followers/whatever. Let them thinks it's going to work out. Then, make a in-game event in which you reveal their plan is not going to work out. Someone it out for them and that someone is probably going to rule the land… PCs are then compelled to act, and may end up looking for allies (which might make them regret their former neutrality).
For option #2: maybe they are thinking « Well, those Orcs seem pretty decent. Looks like they can manage on their own. »
That's a fine line of reasoning, but change the game so that the situation becomes threatening to the PCs or what they hold dear.
- Maybe those orcs doing that well. Maybe they were betrayed, or they're been hit pretty hard by a cunning enemy…
- Okay, orcs have a good shot at it. But a new warlord from a rival clan has taken over and Soria was made prisoner or executed. The new emperor is burning with hate and resent, and once he's done with those demonic abominations, he very well plans to take revenge for the enslavement of his kind.
To summarize, that's what I'd do: whenever players think that their involvement is not required, that their interests are not threatened, change that!
Betrayed, hunted, or otherwise facing impending doom, they will be compelled to act.