If Enix puts their heart into Kenshin Dragon Quest, and it doesn't replace the regular Dragon Quest series, then the Revolution is going to be somewhat pointless. If it does replace the regular series, then Nintendo will be justified, and their victory (particularly in Japan) will be almost assured.
It won't replace DQ, at least not without a lot of kicking and screaming from the fans. People buy DQ to get a NES-style jRPG, not some fancy new kind of RPG with minigames, action-laden battles, etc. Adding a manually controlled weapon to that would drive away the core fanbase of DQ. It'd be akin to giving Mario a waterpack that allows him to shoot and fly: It goes against the very reason people buy the game (in Mario's case, precision jumping and running which were severely compromised by the waterpack).