Retina Display doesn't automatically mean 300+ ppi. If you believe Apple, it simply means 'at the distance you hold this from your eyes, you won't perceive individual pixels'. I have an iPad and I hold it on my lap or a table which is usually 2-3x farther away from my eyes. I didn't do the math, but making a larger screen with that pixel density is closer to the realm of possibility than a 300+ ppi screen and it would still be called a Retina Display by Apple.