Samoa Joe - I've never been a huge fan of Joe. He's pretty good inside the ring but he's as bland and one dimensional as it gets. He's played the brooding, angry tough guy with a chip on his shoulder since coming to TNA and I've never bought into it for a second. A big reason is because Joe doesn't have the physical presence or look to come across as an intimidating badass. I don't know if this is true or not but I've read that Joe has been asked several times by TNA management to lose weight. If they have, he obviously hasn't done it and that suggests an attitude problem. That won't fly in WWE, it simply won't. If the brass asks a guy to drop some weight and he refuses, then he's not going to be very prosperous. Not like they'd be asking for a kidney. Brodus Clay, while still a big guy, dropped over 100 pounds and he's still far heavier than Joe is so if he could, Joe could.
A.J. Styles - Styles would do very well in WWE. Since Triple H started revamping the WWE's development system, Styles is exactly the kind of guy he's looking for. Styles is both a young guy and a veteran. He's been in the business for more than a decade, he's worked in a lot of different indy promotions and he's the overall biggest star that TNA has ever produced. He's got the goods in the ring and he can actually cut a decent promo most of the time. However, Styles has said lots of times that he's a TNA guy. Plus, he signed a long term deal with TNA a few years back that was for 7 or 8 years. I think he's got at least 5 years left on that deal.
Beer Money - Beer Money is quite possibly the best overall tag team wrestling has seen in past half decade. They both are good in the ring, both can talk on the mic, both have personality and charisma. Neither guy has much to crow about when it comes to singles competition, but both guys have potential to be big singles stars. One thing working against them, at least to some degree, is that they're both 35 years old. While still relatively young, they're not getting any younger. If they have WWE aspirations, then I think they'd need to get a move on. However, I'd say both of them are pretty much set on sticking with TNA.
Crimson - I'm not all that wild about Crimson. He has a great look and that's the best thing going for him right now. Also, like Bully Ray said, Crimson has been around for a cup of coffee. TNA may be pushing him hard right now but it's far too early to tell if Crimson has the goods or will fizzle out.
Hernandez - Hernandez is terrible. He's sloppy in the ring and horrible on the mic. Aside from a great look, the guy doesn't really bring all that much to the table. Zero charisma, no personality and he just simply doesn't have what it takes to make it as a singles guy. In my opinion, the guy's a dud.
Abyss - Abyss brings nothing special to the table at all. Abyss was so awful and corny for so long that it still overshadows anything he does. The WWE has several guys already that are as big, or bigger, and are simply much better at doing the same job that Abyss would do.
Kurt Angle - Angle has said several times that he intends to retire in TNA. Dixie Carter will literally give him anything he wants. She's done it the entire time he's been in TNA. He works when he wants to, he takes time off when he wants to, he usually has pick of who he'd like to work with. He got Jeff Jarrett banished for over 6 months from the company that he not only originally owned and founded but who also still owns 27% of the company stock. That's power that Angle will not have in WWE. He'll always be a star and be treated like one, but he'd also have to tow the line like everyone else on the roster.
Jeff Jarrett - As I said, Jeff Jarrett still owns almost 30% of TNA. He's not going anywhere. He's invested himself to TNA in every way.
Mr. Anderson (Kennedy) - Anderson has burned bridges in WWE by often criticizing other wrestlers, some of whom are mega stars in the company, for some of his own shortcomings. Anderson's run in WWE was plagued by several injuries that, when all totaled, kept him out for somewhere around 20 months. I can't be 100% sure about this but he either failed a drug test or he did an interview on a radio show in which he said that using steroids wasn't a big deal. It was one of them or both of them. I know that he was suspended for 30 days regardless. Then there are those that say he's lazy or sloppy, he allegedly nearly injured Randy Orton during his last match in WWE, etc. Anderson has blasted and criticized WWE time and time again so I wouldn't expect to see him back.
Rob Van Dam - RVD has a sweet deal with TNA. He makes more money than the vast majority of the roster and he works a part time deal. If he wants time off, then he's got it. RVD will never be a big star in WWE again and it's hard to blame Vince for that. After Vince finally gives the green light for RVD to be elevated to a main eventer, he gets himself busted on drug charges while he's simultaneously WWE and ECW Champion. It just ain't gonna happen.
Jeff Hardy - Jeff Hardy is a bullet that WWE managed to dodge. Less than a week after he leaves the company, his house gets raided and he's arrested on multiple drug felonies. On top of that, Hardy leaves WWE while he's in the middle of the biggest push of his career and during a time where he's never been more popular. Hardy is someone that's made some bad decisions both personally and professionally and, at this point in time, he's just a liability and a potential disaster waiting to happen.
Ric Flair - I think there's potential that Flair could return. However, the thing is, Flair still wants to wrestle and the WWE's not interested in having him wrestle. I've seen Flair in TNA and there've been times in which he's really been embarassing to watch. Flair is a legend and could be a boon to WWE if used in the right way. The problem is that Flair wants to be used as a wrestler despite the fact that he's 30 years, or older, than most of the current WWE roster.