While I don't fully buy into the AEW hype before it's, you know, national television launch, there are a few things that they do have that one up previous companies:
1. They have a built in following that's grossed a good PPV turn out (not as good as WWE's grant you, but up there with some of it's stiffer competition) and filled 13,000+ seats of paying customers. TNA doesn't have that. ROH doesn't have that. Lucha Underground, MLW, name an indie with a television show and I can tell you that they do not have in such a lucrative or plentiful fan base.
2. They've got a backer whose richer than Vince and willing to invest in the company. That is a big deal.
3. They have national television distribution with a major cable network. Plain and simple, if you have basic cable in America you'll be able to watch their programming. Again, nobody but the WWE has that in the U.S.
4. They've got a more lucrative and inclusive business M.O. Not only do they plan to cater to differently abled fans at live events, but they've also added incentives to working for them like creative control, including scheduling and the ability to work elsewhere if you'd like, and (potentially) health insurance. These contracts have been lucrative enough to draw Jericho away for what he himself has said is the biggest and best contract he's ever received. Considering he worked in WCW during the ATM Eric days, not to mention WWE, that's a big deal.
5. WWE talents are actively attempting to get out of their contracts to get to AEW. Again, hasn't happened since WCW.
6. WWE is in a ratings tailspin at the moment. They could pull out if they completely restructured how they do procedural wrestling television, but that doesn't seem to be in the cards. Tack on the fact that Vince will probably have his hands full with XFL, and this could be the WWE at it's most vulnerable since the mid-90's.
7. Without having more than two shows, AEW's already working on having a global footprint outside of America and has already created working agreements with a handful of promotions.
I'm not proclaiming domination of the McMahon's, and honestly neither is AEW, but there's clearly an interesting change in the tide of how things have been for the past 19 odd years with AEW now in the picture. It may not be the great WWE killer, but it's definitely a business changer.