It's not confirmed. Trailers begin circulating in two-plus weeks.
If 'it's' not Khan at this point, it could be one of the cleverest deceptions in Hollywood rumor control history. And if anyone is 'worthy' of being able to employ such misdirection towards eager fans -and by willing participation of those said very same fans, no less- it just might happen to be the Abrams team.
On the other hand... if 'it' is Khan, then JJ and company have to know that their movie absolutely needs to hit a home run and be the ST that finally surpasses The Wrath of Khan. Yes, have to, and yes, needs. Because comparisons between the two films would be inevitable.
This by no means guarantees the film would succeed in topping Khan; if anything the odds are 'probably' against. But they would have to know that whatever criticism, abuse or negative buzz they receive, they'll have walked right into it. They have to.
So if 'it' is Khan, take 'some' comfort in the fact that they're fully confident in betting their cards on what they've got. For however much or little you think their confidence is worth in your estimation.
And besides, the whole "It's gonna suck" song and dance has been a seemingly obligatory Trek tradition ever since fans heard negative buzz about the death of Spock and dared Wrath of Khan to 'suck' as much as they believed The Motion Picture did. There's no detour around it. The only way out is through.