I don't know that Kurt will be willing to work a full-time WWE schedule. Perhaps that will be something they negotiate. Personally, I think Kurt is one of the greatest talents to work in a ring. If it meant prolonging his career, I think it's in the best interest of fans and the company to grant him some leeway.
Kurt's been in TNA for a good time, now. If he's eyeing the prospect of working with some fresh talent, then I doubt he has plans on retiring anytime soon. With some of the other "older" talent Vince has been signing, Angle seems like a most logical choice!