If you went in with the frame of mind that you could make an rpg for older people because those people have grown with the series I think you would unfortunately find out that too many of those older people have quit playing games or rpg's to make the game very successful. The combat in Japanese rpg's is quite childish in itself.
RPG's will always be a genre for the very young. The majority of older gamers tend to be more into the open ended adventure games than Japanese rpg's.