They seem to be jumping ahead of themselves here. The Vengeance looks more like a 24th century ship. More like a Dreadnought Sovereign class variant.
Meanwhile, they seem to have given up on the TOS era design style. Enterprise, even though its been restyled, still holds the TOS feel with the external Deflector dish, the rotating Bussard Collectors, etc etc. The rest of the fleet is still of the Kelvin era design.
Now JJ has Starfleet fielding huge ships with much later styling design. What does this mean for a third movie? They redesign the fleet to look like Vengeance variants? And so what do you get in the alternate 24th century, Enterprise J designs?