Digging around in the software, you always seem to find easter eggs, that are sometimes intentional and sometimes not. The important thing is that they reveal something about the company, and that’s exactly what has happened with Apple.
A tipster found out that the El Capitan OSX Beta reveals a product that Apple is possibly making: The 21.5 Inch 4K (4096×2304 pixels) iMac, thus bringing the resolution bump to another computer in the Mac line.
Even then, Apple’s 5K iMac is the highest resolution screen in Apple’s lineup. The 21.5 inch iMac could use a quad-core Broadwell processor