#1 Huge match at WrestleMania 35

Dean Ambrose has had a tough two years, having been sidelined for a long period of time due to injury, and then the breakup of The Shield which resulted in his underwhelming run as a heel.
Apart from the match against Brock Lesnar at WrestleMania 32, Ambrose hasn't had a big singles match at the Grandest Stage of Them All. A huge match at WrestleMania 35, against someone like Triple H, whom he teased a feud with on the RAW after Rumble, could perhaps change Ambrose's mind to stay in the WWE.
John Cena's father just broke his silence on his heel turn! More details RIGHT HERE
If Ambrose quitting WWE is a work by the WWE, we may very well see such a storyline unfold in the next few weeks, and we could maybe see a "Career vs Career" match, which would go well with the announcement of him leaving the WWE.
If a WrestleMania singles match against a legend cannot make Ambrose stay, then perhaps there can't be anything else that would change the mind of The Lunatic Fringe.