4: Dean Ambrose

I know what you're thinking, Dean Ambrose is already scheduled to leave the WWE after WrestleMania 35.
And though that is true, at least from the fans' perspective, it has been reported that the company is hoping to re-sign the Lunatic Fringe to a very lucrative contract.
Did you know a top WWE Superstar just wrestled outside the company? More details HERE
If a deal is agreed though, the company will definitely have to push Ambrose more prominently, perhaps into a World championship feud.
Facing off against Seth Rollins could be a great starting feud for the Architect, if he captures the Universal Title from Brock Lesnar at WrestleMania.
If he does re-sign, special care will need to be taken by the company, or else it'll only be a matter of time before the Lunatic Fringe actually leaves for good.