Fool! Enel, the god of the sky, lowering himself to a position below another? A fat, almost toothless bum from the lower realm at that?
Heresy!
Nah but for real, I actually think Enel will show up again and actually be kinda important since he has his whole moon and ancient history lore and whatever upgrades he might have acquired from the moon backing him up. Hell he either could himself be Uranus or have found it on the moon all things considered since Uranus being literally the personification of the sky would fit well with him.
But he is not doing so via serving somebody else. I see him as a complete wild card. Shit he might show up in Elbaf and start shit with Thor because he claims to be the god of thunder or something like that.