#4 Hulk Hogan
Hulk Hogan may be the most popular sports entertainment of all time, but he has an estranged relationship with WWE because of certain remarks he'd made. Time heals all wounds, and we wouldn't be surprised to see The Hulkster back in the company soon.
One of the ways to keep him on screen may be as an authority figure. We all remember Hogan from his run in TNA. He made quite a decent authority figure on screen, considering there's hardly anyone who can match him in terms of microphone skills.
Hogan could bring mainstream appeal to SmackDown Live, a show that is desperately lacking in legitimate stars. A lot of the younger talent could benefit from just being around him.
If Daniel Bryan were to leave, WWE would want a replacement who is a household name to get the same reactions that he did. Who better than the greatest of all time? Whatchoo gonna do, when the General Manager runs wild on you? Say your prayers and eat your vitamins...