NO. simply.... NO.
iPad would NOT need to do 2048..
iPad is 130ishdpi, but to technically be considered a retina display (which is RELATIVE to the avg distance from the user's face) it would only need to be about 200dpi, minimum resolution of 1482x1112 if the iPad is an average of 18 inches from the face.
(in blue would be considered a "retina display")
Image
A resolution of 1600x1200 would be 206dpi MORE than qualifying it as a retina display.
Doubling the current resolution is a bogus and overly expensive notion