Not likely, since it'd sell at about $499 and would be hot, heavy, and thick compared to what they actually shipped.
How do technological constraints today contradict future advances?
The iPad mini's gross margin is around 30% already. You have some seriously off-base ideas about markup and costs.
So let's look at some numbers.
iPad mini estimated costs:
Display assembly: $57
Battery: $13
RAM: $8
A5: $14
Cost of iPhone 5 display (for baseline comparison at same pixel density): $44
iPhone 5 screen area: 6.7 inches ($6.56 per sq in). iPad 3/4 display cost: $127 for about 45 square inches at 264ppi ($2.82 per sq in). Hypothetical retina iPad mini would most likely have a display more expensive than its big brother, since higher density drives higher costs on multiple levels, but let's be generous to you and say $5 per sq in since some of display costs won't scale linearly. At 29.6 sq in, that's $148, a $91 increase in components cost by itself (on a device with a total components cost of around $220).
Then you need the A6X, costing roughly double the estimated $14 of the A5, along with moving from 512MB to 1GB of RAM, or $8 to $12. Then of course there's the battery--the iPad needs 65%+ more capacity just to match battery life with the retina display, so that $12.50 jumps up another $7, easily. That's $25 in cost increases just to make the retina display work.
$116 more in parts. With 30% margin, you're now selling the iPad mini at...$499, give or take. The only cost savings you're looking at compared to the iPad 4 is a somewhat smaller, less expensive battery, maybe a buck or two in aluminum, and a lower margin overall compensates for the more expensive screen.
Even in a fantasy land where you could make a 326ppi screen at the right size for $100, you're only pushing the price of the mini down to $429 at best.
I really don't feel like arguing every single device down to the penny. I did mention over and over again that apple is probably making between 300-500% profit margin. IF these costs you display are even correct they are still making 300% and that's on the BASE MODEL w out LTE.
And IMO, I do think people would pay $100 more for retina b/c apple already priced themselves out of the 'cheap' tablet margin by setting base version at $329. You have your opinion and I have mine.
Apple also makes millions on itunes. Apple just chose not to throw in the retina for they could increase their profit, simple as that. I don't think they did anything illegal. Just another company out for the buck when they could have given us value.
Basically if apple only made $50 on each device sold, they'd still be making millions. Apple sold 5 MILLION iphones alone.