Supposing it did happen, outside of a few weeks worth of TV ratings and a month or two of a bump in buy rates, it wouldn't matter.
You'd think a company that has names like Hulk Hogan, Ric Flair, Kurt Angle, Jeff Hardy, RVD, Sting and talent like Styles, Daniels, Aries, MCMG, etc. would do better and have more recognition but they don't and they can't change it because of who owns the company and who is running the company. Rock & Austin wouldn't benefit TNA in the long-run because booking can't back them up and their huge paychecks probably would finally put the company under.
It's all about brand perception these days for the most part, who is on the roster is almost irrelevant. You can swap rosters and the majority of the people are still going to stick with whatever's branded a WWE show. TNA & WWE are in the same place they are always going to be in, nothing is ever going to change that.
And why the fukk is this guy on the roster page?
http://www.impactwrestling.com/roster/Wrestler-Roster/item/2920-Mark-Haskins
Isn't he the one that has had only 2 or 3 matches and nearly killed himself in all of them?