A Nintendo action RPG, good idea or bad?

[Iyasu]

I'd like it if it were for both, and you could play together across the systems. Then everyone would have their own screen to explore.

And I'd hope that a game like that would rather improve the sales of the third party games, through increasing the audience.
I don't feel like the market for (A)RPGs on the 3ds is overflooded (at least in the west), so people should have enough time for both Nintendo and 3rd party games.