#3 More creative control of his character
To be honest, the only reason why Ambrose decided not to extend his contract with WWE is because of the on-going direction of his character.
Ambrose's heel turn was one of the most awaited character changes of all time, but as already seen, it was a total bust since WWE's creative team miserably failed to capitalize on it.
Therefore, Vince McMahon might throw Ambrose a lucrative deal of "more creative control of his character".
If this is one of the reasons why Ambrose does not want to extend his contract with WWE, this move could seriously make Ambrose stay in the company even for a longer time.
#2 Top face of Monday night RAW
Before the last superstar-shake up took place Ambrose was working on SmackDown Live brand.
There he was the blue brand's top face while AJ Styles was their top-heel.
Since Ambrose has traded brand and has moved to WWE's flagship show, RAW, he has only remained in limelight despite being one of the top-performer of the company.
Therefore, as Roman Reigns is already out of the picture, hence, making Ambrose Raw's top-face, at least for while, could work for the company since Ambrose has never become top-face of WWE's flagship show.
That said, if Vince McMahon decides to pass the light from Rollins to Ambrose at least for a while, I think, Ambrose might be open to re-signing with WWE.