They can only be retina displays if the use Apple's patented tech. and there have only in ghe last 8 months had phone with a similar PPI, the design and other features that continue to allow iPhone to win head to head comparisons even when the other phone has a higher PPI, is what make it retina. To be so they would have license Apple's design which won't happen.
You are absolutely clueless. Do you think Apple have some magical patented screen technology? Do you think they manufacture their own screens? They're just high-res IPS displays which they buy off vendors like Samsung or LG, for god's sake. Good displays no doubt, but nothing other manufacturers can't match. Case in point: HTC One.