Constantius II doesn't die in Cicilia

[Grouchio]

http://en.wikipedia.org/wiki/Constantius_II
I was wondering, what if Constantius II didn't die en route to face Julian in Cicilia in November of 361 AD? Would he possibly be able to defeat Julian and rule the Empire solely? Could he have had children who might have succeeded him? What does this mean for the spread of Arianism, Constantius' religion? How might this effect the barbarian invasions? Could someone make a story outta this? I wanna know!