I think he could give them a ratings Spike but a ratings boost, I am not so sure. The thing I see a problem with regarding TNA is that I think some people regard Impact as some offshoot of WWE programming (like Velocity, Sunday Night Heat used to be) and therefore don't know that this is a different organization. Yes, the presence of former WWE alumni does not help either with that perception.
The biggest thing that I think hurts TNA and just remember this is a viewpoint and not a hard fact like some people here like to make is that TNA lacks a true presence outside of its product. Meaning that other than action figures and its website, I see very little in the way of licensing with the company. They haven't found another developer for their video game franchise (which I think is a HUGE factor in a company's success these days) and so forth.
Believe it or not I don't think the former WWE guys in TNA hurt all that much, I truly think it's the fact that you see very little in the way of TNA licensing. Also the lack of traveling outside the Impact Zone up until now I am sure trapped TNA in those ratings too or helped contribute to that. The thing is this, they are starting to fix that at least and have begun to go on the road.
Again, Rome wasn't built in a day and I think TNA still has a chance even amid all these Hogan leaving rumors. It's a wait and see thing like always. Again I am sure Cena could help spark an interest if he ever went there, but it's not like Hogan going to WCW in the 90s.
The difference between a possible Cena jump to TNA and what Hogan did in the 90s is that Hogan came into an established organization that had roots going back to the 1930s and an established group of stars (Steamboat, Flair, Sting, Vader, and others). TBS's specials like Clash Of The Champions were huge ratings grabbers so it's not like Hogan just walked into something brand new here and legitimized it instantly, WCW was a lot more established than people might want to think in retrospect. TNA on the other hand despite its presence of veteran talent and a few young and talented guys does not have that benefit.
"Wrestling" isn't the problem, most casual and new fans expect the drama (thx wwe), the live soap opera type production. Allot of people finds too much wrestling "boring" if you think because there isn't enough wrestling, then why is roh not bigger then tna or wwe?
TNA needs to get a healthy mix of both wrestling and the drama. They need to get tenay out of there, i be like holly shit! and tenay and taz just babbles on about something, showing no emotion what-so-ever. But as far as dixie fire tenay, it wont happen because she said that he can set behind the both as long as he wants and she owes everything to him (basically he's safe), but they need to get someone up there that shows emotion.
They need to slowly start moving out of the impact zone and going to venues that they have had success at, because the impact zone is dead, not real fans of wrestling and just goes there because it's another part of universal studios, thus is the reason why i don't blame them for using canned heat and hiring "fans" to cheer and boo. The fans what makes the show seem boring, and story lines seem less important. the fans are setting on their hands + the impact zone makes the show seems small time and less important to the causal fan.
Look at the places where they got a nice size crowed, then next week they go back to the impact zone.. you can tell a big difference! the show seemed more important.
So what tna need to do is this..
1) Remove Tenay from the booth or give him a limited role at the booth and get borash with taz and borash (he done really good the first time he was up there taz/borash had that click)
2) Get out of the impact zone
3) Make russo give suggestions instead giving unlimited creative control (he does have good ideas sometimes)
4) find the right mix of wrestling and drama.
5) keep a few older guys, but don't make the whole show about them.