While I believe gen 6 is a very likely outcome. There are a couple things based on history that are making me hesitant.
1. In most generations there has been a pokemon shown before that generations games came out. Usually through the anime or a spinoff game. (Togepi, Manaphy, Zoroark, etc.)
2. There has not been a console game for the 5th generation. The only way I could see this happen though is if it was just a monster of a game such as the rainbow rumor that warrants the hope involved.
I personally hope it is going to something no one expects which will completely revolutionize the series.