I was just about to post a thread regarding who could come in to TNA...so this one works.
I've read on some wrestling sites that they have not one, but two, "huge" names that are signed and coming in. I'm very curious who these HUGE names could be. I think everyone expects Ken Anderson to be one. I don't think he's "huge" though, if he were signed right when he was released then yes, but not now. The other most obvious one is RVD. Beyond that I really don't know who could be considered such a big name that could reasonably sign with TNA. Also, if it's not a wrestling, then really I have no interest.
Heyman is a good guess, I didn't think of that, but he's more valuable as a behind the scenes guy and I think it's obvious that he wouldn't be given the power he would want/need. There are a few "big names" that I can think of but I'm not sure that I would believe pretty much any of them signing until I see it. Like I said, I think the two bigger names people are expecting are Anderson and RVD (and I'd bet Anderson is probably a lock at this point). Others:
Goldberg: They have Hogan, Hall, Nash, Waltman, Sting, Steiner...so it only makes sense that they'd make a play for Goldberg. I also think that he has some ties with Spike. But we've heard in the past that he simply wants too much money. I don't knwo how much of a draw he would be really. I personally have never found him interesting and I don't know if he's a name that current fans would really care about that much.
Randy Savage: Another ex-WWF, high profile WCW guy. He's a huge name no doubt but he can't go anymore either. I could see him turning up in TNA and if he's in shape I might be interested...but I'm sure it would get old fast.
JBL: I cannot stand JBL and do NOT want to see him in TNA, but he is a familiar face to this generation of fans. I don't know why he would choose TNA at WWE at this point though. He likely would get more money (and a reduced schedule if he wrestled) in WWE, and has a shot at the WWE HOF, even though I don't think he's anything special. I think we have a better chance that some others of seeing JBL in TNA.
Shane McMahon: I don't think he would ever come to TNA simply because there is still plenty he could do at WWE and it is an family business. I just can't see him bailing wealth, success, and family just to "try something else."
The Rock: Let's just get this out of the way right now. The Rock will not be in TNA. He's a Hollywood career guy now. If he was going to go back, it would be as a guest, and it would be to wherever he could get the most exposure, and that would be WWE. He will 99% never wrestle again, and I'd say he's 99.999999% sure to never appear in TNA.
Brock Lesnar: Now here's an interesting idea. Another long shot, and I don't see it happening. But let's say that Lesnar is hurt enough that he cannot fight legit. He may still be able to do something wrestling wise. Obviously there is the Spike TV connection there so that could help. I do see Brock as a "I'll go where the money is" kind of guy, but he has also done so much. If the price it right, and he is unable to fight MMA, I could see him come into TNA. I also wouldn't expect any announcement if/until we find out about his UFC stats, and then only if he simply cannot fight ago. While I don't really expect this to happen, this would truly be a surprise and a big name signing.
Other than that, I really can't see any "big names" that are out there. If I were forced to pick a name right now I'd have to go with Ken Anderson.