You know what's kind of funny to me? The cover makes it look like Jon's "S" shield is Doctor Fate's, and that she's holding her finger to where her lips would go to say "shhhhh".
Good memory! The idea that Doctor Fate may be from even further in the future didn't even occur to me. In the interview you're thinking of Bendis said "Doctor Fate not only feels not-retro, but Doctor Fate works on the team like she's already 30 years ahead of them, like Doctor Fate is working beyond the Legion already."
I took that to mean that she, as an avatar for a lord of order, was already kind of above the Legion. But the fact that Bendis specifically uses "30 years ahead of them" rather than just saying "Doctor Fate is working beyond the Legion already" and leaving it at that seems to indicate that there's a possibility that she's from the future.
Maybe Doctor Fate, as the avatar of order that she is, traveled back in time to the Legion's time to stop the kids from doing something crazy. I mean, they're already messing with the time stream by having Jon there, but now they're talking about literally changing past events (the Damian thing).