Yeah you make a good point about being worried on the new versus old fans dividing. Considering FFVII was the first of the FF that got a large US sale which started FF up in the US. Before FFVII, it was a rather unknown name to US gamers. But everyone knows about FF now, and few people know about DQ right now. But this is the big US showing for DQ, and considering how much they are trying to hype it up and get the US audience on board, it will probably be a big seller, heck any FF fan will probably get since it is something from Square and a RPG. So I definitely imagine a new fan base growing for DQ, would not be surprised if it is not as fanatical as the FF fans.
Considering DQ is not allowed to be released in Japan on a work day because it makes everyone leave their job and buy the game and sit as home playing. Which is quite amusing the first time I heard that like 4 or 5 years ago. It just surprises me they have a law to prevent a game from being released during a work day because it ruined productivity that much.
Just goes to show how loved the series is in Japan. The commericals say that it has sold over 4 million copies I think, which is more copies than a FF game gets worldwide almost. Square-Enix must be happy.