#4 Returns as a solo tweener
Lest you forget, Dean Ambrose is a former WWE Champion and carried SmackDown Live on his shoulders for a large duration when he was on the brand. I can absolutely imagine him going solo and existing between heel and babyface territory. All I know for certain is that it would definitely freshen the character up. It may even let him play an actual 'lunatic'.
As a tweener, Ambrose could take the fight to the Dogs of War. But he can also battle The Shield and contest for the Universal and the Intercontinental Championships down the line. It would elevate the character because at present, he's little more than a sidekick.
Yes, The Shield is red hot right now. But this decision may yield better long term results.