With 4K TV's and displays coming that are able to display content greater than the rMBP can, the retina screen is going to be outdated soon. The resolution for the rMBP is too low for 4K content.
Perhaps in a future rMBP, the resolution / PPI could be bumped to 3840 x 2160 so that 4K content can be enjoyed to the fullest.
Perhaps in a future rMBP, the resolution / PPI could be bumped to 3840 x 2160 so that 4K content can be enjoyed to the fullest.