Since the "thirty years" line came from Iger and not from Abrams or Kasdan or Kennedy, I'm taking that news with a grain of salt. He's probably just saying that because it's been thirty years IRL since Jedi was made. Setting this at the forty year mark the books are currently at would make way more sense, since Luke's son is now almost twenty.* It's also worth noting that the actors in the OT were older than the characters they were playing, so setting it an extra ten years later basically evens it out.

I am, of course, still assuming that the existing EU isn't getting steamrolled to fit with the new movies, which remains a distinct possibility.

*Then again, who knows. There's been a lot of rumor and speculation from all the casting news. Abrams could very well intend Luke's son to be a kid only Anakin's age in Episode I. The guy made a whole movie starring a mostly younger cast (Super 8), so it's not like he'd be a stranger to this kinda thing. Also, Iger's line about "a new trio" can probably be taken at face value.