Very interesting thread.
I dont think ECW could have lasted much longer, even if it had made it another year or so. Heyman was on his ass at the time, the company was losing money hand over fist and you could see it was on its last legs. The only hope ECW could have had was that a wealthy backer had stepped in with enough money to keep it afloat and help it to grow, as has happened with TNA and Panda Energy.
As for WCW?? Well, I think they would be like the TNA of today. The gulf between WCW and WWE at the time that they went out of business was huge. WWE was obviously at its peak, while WCW had become a running joke, with actors and storyline writers as World Champion. I still think Vince would have ended up signing the majoirty of WCW's top stars, he just had the money to do so.
There would have been no TNA, as Jeff Jarrett would have remained in WCW rather than starting up his own promotion, and I do think that as WCW regrouped at a smaller level (think TNA after its debut), they wouldnt have been able to afford the contracts of guys such as Nash, Hall, Hogan and Goldberg, and these men would have jumped back to the WWE in order to make their money there. This would have allowed WCW to focus on building the next generation of stars, such as Sean O'Haire (who would have become World Champion eventually), the rookie AJ Styles, Chris Harris etc...men who can perform in the ring, unlike the dinosaurs who WCW kept at the top of the card.
Using a combination of rookie talent, and some of the older more experienced wrestlers (such as Sting and Ric Flair- who would have remained loyaly to WCW), WCW would have survived, but on a lower scale. Fast forward to 2011 and WCW would be where TNA is now, bigger but not really capable yet of mounting a challenge to WWE. They would have run their own training camps to find the new talent, perhaps snapping up wrestlers such as Batista or Brock Lesnar, before the WWE spotted their potential?
WWE itself would be in a similar position to where it is now, but perhaps a littler better off as with WCW remaining in business (albeit on a smaller scale), Vince McMahon would not have become as complacent as he did without any competition. He would also be able to steal some of the new talent created by WCW, such as Styles and O'Haire, when they reached a level of stardom which would have benefitted the WWE (think Chris Jericho, The Radicalz etc.) This would have prevented WWE from becoming as stale as it has become in recent years.
All in all, I think had WCW survived then the wrestling business would be in better shape than now. We wouldnt have seen a continuation of the Monday Night Wars, WCW was too far gone for that, but just having 2 companies in the US with big names would have benefitted the business more than having WWE as the 1 dominant company with a brand new promotion in TNA.