James Wilson doesn’t think we’ll see a retina display-equipped iPad:
When Retina Display hits the iPad it will be the apocalyptic moment when all other tablets self-implode. Look at your iPhone 4 and its still-unbelievable display. Now look at your iPad and imagine that display on that device. Make no mistake, when Apple makes an iPad with a Retina Display it’s game over for the current competition.
Problem is, it would also be game over for the iPad 2. I don’t think any price difference could make the iPad 2 a compelling option in the face of a beautiful Retina Display on an iPad 2.
Convincing argument. What I think it comes down to is cost. If Apple can get a retina display-like iPad screen’s cost down enough, they’ll make it an iPad-wide feature. If not, they’ll wait until they can, or release a pro version.