Ric Flair is a spotlight junkie if there ever was one. It would be nice if Flair used his experience to help the kids from backstage, but I don't think he would do it. If what they say is true and Ric Flair WAS the man, then that's one thing, but he still thinks that he IS the man. I hope he's saved his $$$ because it's time Ric Flair faces the fact that it's over.
In my opinion if he came back to WWE, instead of helping the young guys, he would be wanting to steal air time from them. I love the occasional appearance from the vets such as Bret Hart, SCSA, Piper etc. But Flair is different from those guys in the effect that he still thinks it's HIS spot. So to answer your question, WWE could bring back Flair, but I sure as hell hope they don't.
Flair has always had a reputation for "being There" for the younger guys, whether he was going out of his way to make Lex Luger look great in the ring when other stars did not want to, putting over loads of younger talent through the years from Goldberg, Benoit, etc - helping to elevate existing stars like Edge, Jericho, Orton... in WCW and WWE Flair was known as a guy who did whatever was necessary to make the product a success. That's why he was one of the first people approached about joining WWE when they purchased WCW, not Hogan, not Nash, Flair. Vince knew that even if he wasnt wrestling he was valuabe to the product and the locker room.
Compare that to Hulk Hogan's rep and they are like night and day.
As for what he offers now, much the same as he did in 2002. He is way over with fans, great on the mic, can play a face or heel convincingly with little difference in character. He'd be a great GM or manager. Plus he'd likely be available on a regular basis, not the occassional "I need a payday" guest spots that Steve Austin makes.
TNA has grossly misused Flair, he should have been used as the mgr & mouthpiece to get talent like Beer Money & AJ Styles over so the company can start building around their own talent and not just the ageing vets on their last days (Sting/Kurt Angle) or the mid carders already discarded by WWE that the wrestling audience is not that invested in (Hardy, Kennedy).
As far as would Vince take him back, remember Vince had a 500 grand per year contract on the table for Flair in 08 which he turned down so he would have more control over his own bookings (in hindsight, not a great move). Flair himself said in a radio interview back in 03 that at the end of the day Vince is about making money and if he could pump up ratings, get talent over, sell more DVDs, etc he would bring Flair back in a heartbeat. If he was willing to bring back Hogan after he testified against him in federal court and almost got him sent to jail, then jumped ship and took his name and trademarks to WCW, if he brought back Brett Hart after all the times Hart skewered him publicly, literalyy blaming him in the press for his brother's death like Vince kiled him, if he brought back HBK after all his prima donna outbursts, general refusal to put anyone over in the ring, and his well documented drug problems, their is no doubt in my mind that he'd bring back Flair who has never crossed Vince publicly and always maintained a professional relationship with him.
The biggest problem Flair has in TNA (besides lousy booking with affects the product as a whole) is they don't have the cash flow WWE does. When you read reports that wrestlers don't get waling around money when they are working overseas or that they do not financial assistance with surgeries for injuries suffered while wrestling you can see this outfit handles things differently than WWE. I doubt they have the catered buffet dinners WWE has for talent before shows (correct me if Im wrong on that) and I doubt the payoffs from house shows or PPV are even close to the same. Ive also heard stories that pay is not regular, and sometimes it takes a very longtime to get bonusses, etc.