The move to Monday nights that TNA tried before (it's hard to believe that it was almost two years ago now!) didn't work in their favor, but I think that the live aspect was a fantastic move. The shows TNA put on in early 2010 on Monday nights were better than the shows they were doing before, but they were trying to rely on Bischoff's old tricks. Those tricks involved putting Hogan & Flair into matches, and relying more on older established talent. Granted, they were trying to push AJ, Abyss & Joe at that time, but things seemed to revolve mostly around RVD, Hogan, Flair, and "The Band".
Personally, I think that TNA would eventually get even lower ratings if they moved to Monday nights right now, due to the competition from WWE. I don't think anyone's trying to argue that point; WWE simply has a bigger wrestling audience. The wrestling fans are going to tune in to WWE, even if TNA were to continue running ads for Impact ("Live Right Now!!") on USA (during Raw).
TNA's major problem right now is that they're running a taped show. I think that Impact would get bigger ratings if they ran live shows on Thursday nights, in their current time-slot. I know that their current schedule doesn't allow for this, and they would stand the chance of losing some of their current roster. Guys like Kurt Angle, etc like the current schedule, because they can tape a whole month's worth of shows in one week...then they only have to show up for the PPV at the end of the month.
TNA should try to go live every Thursday, even if they stay in the Impact Zone. They could try doing every other show live (like they did two years ago), but the problem with that is that the live shows turn into "supershows" that TNA feels like they have to treat live PPVs. The live shows I remember from early 2010 involved RVD beating AJ for the World title, Jay Lethal winning the X-Division title, and the "big" tag match, which featured AJ & Flair vs. Hogan & Abyss. Obviously those matches were PPV caliber, and they gave them away on free TV...TNA was trying to add PPV excitement to their weekly show, and it didn't work; at least not in the way they wanted (or expected).
Moving Impact to Monday night on a permanent basis might work in the long run. I don't have a crystal ball, nor do I really know anything about TV ratings or anything like that. Who knows? Now that TNA has more established "non-WWE" stars, they might stand a better chance than they did in 2010. If TNA continues to remain a taped show, then they'll ALWAYS stay behind the WWE in every aspect. It's the same reason why Raw is the WWE's "A show", and Smackdown is the "B show". If Raw was suddenly taped ahead of time, and Smackdown was the live show, it's completely possible that the ratings would flip-flop for those two shows. Wrestling works better when it's live on television. It always has, and it always will. In my opinion, TNA needs to worry about presenting Impact live (on a permanent basis) before they should worry about their time-slot. They're making money with their current situation, though...so I don't think we'll see such a drastic change made in the near-future. At this point in the game, changing their time-slot/day the show is on would be entirely too risky.