#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.
Charlotte Flair to return and wrestle a CURRENT CHAMPION?
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.