Looking at the Marvel Universe, things have been in a downward spiral for the heroes for awhile now, haven't they? And most of that has been them squabbling amongst themselves, or being under attack from their friends and allies. So is Dark Reign the point all that turns around?
From Disassembled, to House of M, to Civil War, to World War Hulk, to Secret Invasion, the people that wind up causing trouble for the heroes are people who were either their friends, or were pretending to be their friends. It's Wanda going out of her gourd, or Iron Man vs. Cap, or the Hulk looking for some payback, or oops! Jarvis was a Skrull, oh no! The heroes can never get on the same page. They're divided on what to do with Wanda, or they disagree about the Registration Act, or they aren't sure about helping the Illuminati with the Hulk 'cause maybe they deserve it*. When the Skrulls stupidly dropped an army in New York and started blowing crap up, the heroes got their act together for awhile, but once the fight ended, it fell apart again.
Now it appears they'll be up against a cabal of evil** that is, in theory, going to be more subtle. A brief team up to punch people won't fix things (again, in theory). The good guys might actually have to play well together for some time to turn the tide and get things straightened out. Who knows, they might actually talk over the differences they have with each other, mend some friendships.
It seems that with the people who'll be driving Dark Reign generally being outright villains, the heroes should all be on the same side in this one. Actually, this would be a good test of Cyclops' new style. Hey Scotty, Emma's gone evil again, will you send X-Force after her like you did Cable and Bishop? Or will you be soft on her?
As for why everyone is listening to Norman, I've only been able to come up with one (in-story) explanation. Post-Secret Invasion, Norman's in charge of all the governmental super-stuff. SHIELD's gone, the Initiative's gone, everything has been, as far as I can tell lumped into one big group that Norman runs. So theoretically, he could threaten to just send wave after wave of this army he now has at anyone who won't play ball until they're destroyed. He's already demonstrated he can play the media, and the imbeciles that make up the public in the Marvel Universe, like a harp from hell, if I may steal from Batman Returns. He can make up some line of b.s about why he has his people burning the X-Men's shiny San Francisco headquarters to the ground, or why they're invading Latveria or Asgard, and people will buy it. And sure, lots of his resources will get killed, but it's not like Norman would care. He's crazy enough to do that, and the others might simply figure it's better to go along with him than waste time on big stupid fights that will drain their available resources.
I'd be fairly disappointed if most of the others aren't at least planning how to stab Norman in the back. Loki certainly is, while Doom is probably settling on a scheme where he tricks Norman into doing what Doom wants, without that being readily apparent to anyone else.
* Hey, that would be what I'd be thinking if the Hulk says he wants to smash them for tricking him shooting him into space, and then blowing up his planet. Granted they did not actually do that last one, but I'd have serious doubts about getting between them and the Hulk. Which is why I'm not a superhero.
** That's perhaps unfair to Emma and Namor, who may well be there just to gather information for their allies, but given the way things have gone the last few years, until they actually demonstrate that's what they're up to, I'll assume they showed up because they're on board with Norman.