I don't rly care about the story but Jim should live. And Kerrigan may die, prolly the human, sorry, terran campaign will be the last one where the MO is to kill her.
I read the SC&BW stories on SC2 website but not sure. So we have UED and Mensk is the admiral or 'leader' of ued? Then there were the rebelions, forgot who leads them.
Mengsk is the leader of the Terran dominion, which replaced the Confederacy which is the government of the terrans in the sector. The UED were from earth and were lead by Admiral DuGalle and where annihilated at the end of Broodwar, although apparently there are a few pockets of survivors around still.
The Rebels are lead by Jim Raynor who resist Mengsk's government.
The Kel-morian combine was mentioned a bunch of times, which is just a second powerful Terran faction. Looks like they are in a position to be in power in the story, so that could be expected.
Also the Umojan Protectorate is being featured more prominently. The last SC book took lots of time talking about them, and the books are generally written to be closely tied to the game's story.
So just to reiterate the Terrans have two large powers in the sector, the Dominion and the Kel-Morian Combine. Jim Raynor leads a bunch of rebels against the Dominion, The Umojan's are an independent colony, and the surviving UED are still floating around the sector.
That is the current position of the Terrans at the beginning of SCII.
What is likely to happen is what happened in WCIII is they are going to introduce a lot of new characters, particularly to set up replacement for characters who will be killed, and to add more variety to the story.
Chances are either Jim and Kerrigan are going to survive for a later game, OR they are going to have a big finally where Jim makes good on his promise to be the one to kill her.
The Zerg lack any sort of other heroes, since all the cerebrates are dead now. The Protoss also had heavy losses where almost all the recognizable heroes (Aldaris, Fenix, Tassadar) were killed leaving only zeratul and Artanis. Artanis seems to important to die now that he is the "leader", and Zeratul is either going to go out with a bang, or fanservice will keep him alive.