I think Apple will probably update both sizes of iPads at the same time. And I think late summer or early fall is as good a guess as any for the next update. Also, with the 128GB model that was recently released, I would guess no sooner than 5 or 6 months from when they were released.Do you think Mini2 is in the Fall?
I think Apple may decide against 6 month updates if they're going to get sued for releasing updates too fast. In all seriousness there will be whining of updates happening too fast and too slow unless updates only happen once a year or less often, then there will just be whining about the updates being too slow.