The ff series is HIGHLY overrated. The only people who are like "FF pwns everything" are either A never played much rpgs or/and B Never played much FF rpgs. There are many bad ff games, and many rpgs are better than the best FFs, so I don't think we should even not their statements about where rpgs will go.
Edit: ALso its not even the highest selling rpg. I.E pokemon, various wrpgs, even some series like dragon quest and kh(kinda like a spinoff of FF) could compete.