I wouldn't be surprised if the reactions over RSE and it's changes are the reasons why GF seems reluctant to change up the series. Ironic, people complained that Johto relied way too much on Kanto, yet threw a fit when their precious Pidgeys and Rattatas were absent from RSE.
Well honestly I never saw the problem. Everyone waits to see the new pokemon from a generation, but in RS the first thing we really looked for was the old rattata and pidgey, and when they were not there and we actually got to see the new pokemon right from the start and onwards (minus caves that had geodude/graveler, zubat, machop, magcargo/slugma and the safari zone pokemon) we complained to me that does not seem right.