Re: when and how will AJ Styles return?
Longish break then he'll come back, still as a face but someone who has something to prove and is utterly focused on getting the title back and proving himself.
This may mean he'll be a darker face than we are used to (maybe refusing to run in and help other faces if they're in trouble, refusing pleas from Dixie or whoever to help out with whatever turmoil is going on at the time). But essentially he won't be a heel and he'll still be a good guy. He'll just be utterly focused on achieving his goal and be a "man on a mission" - too intent on proving himself to bother with whatever else is going on around him.
He'll also be booked strong with winning streak to show his fight back from his "Year of Hell."
Hopefully, by the time he gets to contender level, Aries will be champ again and we can see the much-anticipated feud between a strongly booked, refreshed AJ and good ol' A Double.