The newly revealed Luigi's Mansion 2 won't be developed internally by Nintendo, but by Canada's Next Level Games, the studio behind the Wii version of Punch-Out!. Nintendo's Shigeru Miyamoto is supervising the project, however.
I don't care what anyone says Luigi's Mansion was a great game (in my top 20). As long as they stay true to the core concepts and expand upon it, I'd imagine this would be pretty hard to screw. After reading some articles it looks like it's shaping up to be a great experience for us fans.