They could surprise with 2048x1536 like the new iPad. That would give a pixel density like the iPhone 4/5. In any case, yes, the ratio will be 4:3 and it will run all iPad apps unchanged. Something tells me that Apple won't want to make new products that don't have retina displays. However, in this case they need to keep the price point low so they should probably stick with the lower resolution and make the jump maybe next year.
10/12/12 at 2:23pm