Im actually expecting new iPads by summer that will look like this:
iPad 2 16GB $299
iPad 4 16GB $399
iPad 4.5 16GB $499
I think a new iPad will have essentially the same internals as the current iPad but with design stylings from the Mini. Same processor, screen resolution, but thinner side bezels, one light bar instead of 2.
iPad Mini 16GB $229
iPad Mini 2 16GB $329
I think the iPad mini 2 will house the same resolution screen, but with an A6-class processor. I also believe Apple launched the iPad Mini, with the poorer specs, to establish the $329 price point they wanted. This way, a new iPad Mini version isn't labeled as a "price increase", but rather a replacement and a price drop. They were just setting public expectations for the future.