Yes, everyone's pretty much summed it up. Not only would the army of hyenas pose a huge problem - and realistically, hyenas aren't much intidimated by lions either - but the lionesses, realistically, had no way out and simply could not challenge the lead male. Unless and until another lion came and challenged Scar and won, there was no escape for the lionesses. I applaud Disney, actually, for sticking to the realism of it; when I watched TLK, I was quite surprised at how much they did stick to the pride's actual "values." Strong as the lionesses were (and are), they just didn't have a choice. A revolt would not be possible without a male lion to challenge Scar.
In reality, lionesses are only able to submit to the winning male (whoever wins in a challenge for leadership of said pride). As I said above, unless and until another male comes and challenges that male's leadership, the females are only allowed to do as their current leader dictates. That's it.

And after a few years, a male from...ugh, I can't remember the name for the group, but outside of said pride and he challenges the male for leadership.
Sorry, I know I'm not making much sense. I'm currently sick, so. xD