No, we cannot assume that. The Retina iPad resolution was introduced at very short notice, and the Retina MBP was introduced with no notice. Apple gave notice of the original iPad so that developers could be ready for a new interface style. I don't think they will have to do the same for a new screen that requires rejigging of existing interfaces.
The link a few posts ago mentioning the long-screened iPhone in the Eyes Free section of the WWDC Keynote makes me think it is true. I just checked that section on iTunes, it is definitely a longer screen shown.
