The WWE Network killed any chance of another big wrestling promotion being able to compete. WWE now has so much content that you can watch 24 hours a day that a casual fan could theoretically just stick to that. How can a promotion doing a 1-2 hour show a week compete with ppvs on Sunday, Raw on Monday, SD and 205 Live on Tuesday, NXT on Wednesday, all the old WWF/E, WCW, and ECW ppvs, old episodes of Raw and Smackdown, the UK show coming, plus all the other content for $10 a month?
I don't think another overall company will ever become bigger. Or at the very least, there is nothing out there currently that I expect to overtake it. Never say never, but the network should secure them for a very long time.
But another SHOW could EASILY usurp Raw/SDL/NXT..and not just critically like Lucha, but ratings/exposure wise.
The WWE has stagnated this industry to an incredible degree creatively. The
Conservative Carny Complex (tm) infects every aspect of everything they put on. They are never on the forefront of anything. They are never really brave or transgressive. Their attempts at connecting to pop culture are laughable.
The fact that there is MORE WWE wouldn't factor into a casual fan. Hell, it likely hurts (And would continue to hurt in the face of actual competition) them to some extent. Most people aren't trying to watch 8 hours of ANYTHING a week, let alone some wrestling.
If someone competent got involved, the WWE would have it's lunch eaten pretty quickly.