In my opinion, TNA has to take one or more of the following three steps to truly keep Vince McMahon awake at night.
3. Hire Paul Heyman as head of creative
Paul Heyman's critics contend that his promotion, ECW, never rose above third place and went out of business in less than 10 years. However, that was because Heyman tried to micromanage every aspect of ECW's business operations. The wrestling, promos, and storylines of ECW are legendary. With Paul Heyman directing TNA's creative plans, the promotion won't need to copy anyone else's storylines.
2. Focus more on its UK market
I'm not suggesting that TNA will become more popular in America by leaving America. However, TNA's best crowds are always in UK arenas. The episode of WWE Raw that took place after Wrestlemania 29 has already reached legendary status because of its amazing crowd. A rabid crowd is infectious, even to fans watching on TV. If TNA could film more episodes of Impact Wrestling in the UK, it would indirectly spawn excitement in America as well.
1. Sign a top WWE wrestler (John Cena or CM Punk)
I know this sounds like replicating failed business models of the past. However, that aforementioned list of WWE wrestlers would pale in comparison to a surprise run-in by John Cena or CM Punk on a live broadcast of Impact Wrestling. TNA would have to keep it a secret until it happens, which isn't as easy today as it was 15-20 years ago. And they would have to do it soon as rumors persist that Cena and Punk's injuries are mounting in the WWE.
At the end of the day, it's possible that Vince McMahon cannot be dethroned and the WWE will never be challenged again. The NFL put the old AFL and USFL out of business and is now the most powerful pro sports league in the world. It's also possible that a large portion of old-school wrestling fans jumped ship to MMA and they are never coming back. But TNA has to take a different approach if it ever hopes to compete with the WWE.