Things go badly for the resistance - named The Voice Unheard - and then they get worse. Still, they fight, because otherwise they bow to Doom, to his regents like Medusa, and they can't help the people they need to help. The Hulks, the people who need medicine, those are pitted against once another although they don't have to be.
Medusa shows herself to be more ruthless than I'd remembered, but she has no good choice: if she's deposed, who knows who Doom will put in her place and if he'll punish the innocents in her domain. He can easily use them to hold her hostage by implying or telling her outright that he'll put a Maximus - possibly a less sane one than we're used to - in her place should she fail him. (That would mean death, destruction, and terror for her people, a people that Medusa has always protected. Even when she was younger, in Once and Future Kings, she rails against another fascist in power, a man who abused his power. Doom might do that, but by keeping power as Regent, Medusa can mitigate the harm he does by taking on his threats and not allowing herself to fail and for her people to be devastated by Doom through her compliance.)
To get at Doom, she'd need a lot more power than she has, so I'm not sure what else she could have done. So many people deify Doom at this point, and he has multiple Thors - that's right, many Thors, including a Dazzler Thor who shows up in a later storyline in A-Force - that not many are willing to acknowledge his faults, much less rise up against him. She couldn't possibly stand up against him alone, nor gather the power she needs to fight off an army of Thors - and Doom to boot.
Black Bolt may not be a Regent, but he remains a leader in name and at heart. When his people, The Voice Unheard, are cornered, he sacrifices himself.
Note: I'm not sure how the royal family works here. Medusa seems to not know Black Bolt at all, although they're first cousins. Karnak and Triton are both working for The Voice Unheard, but don't acknowledge if they're brothers or not. Gorgon is working for Medusa, further fracturing the family aspect. (They are all, in fact related.) I mention Maximus, but I can't remember if he or Crystal show up in this mini-series. I remember some details at the end, but not this. It would be confusing if they didn't, because Nur and Auran are lesser characters in Inhumans mythology and yet both are used. To great effect, but it shouldn't be hard for Soule to slip in the two remaining royals in my opinion, even in a less prominent role. Also, Maximus is just plain fun and having him be sane would be a super fun twist that I can't believe hasn't been touched upon yet. Huge missed opportunity.