Yeah, the waiting to see which (if any) of these rumours turn out to be fact is the hard bit
I just think it's hard to make use of a tablet in any compelling way if it wasn't there for the digestion of multiple content. It's too much of an expense to use as just a console interface, and with very limited applications. All the applications of it are better done as a self-contained item, that the focus of what you are interacting with is also what you are looking at. Low barrier of entry for a controller is also crucial to enabling more than one person to get that experience. If this new experience is compelling, they'd want everyone to enjoy it.
But ignoring the expense of being able to do it, 4 people sat around looking between tablets and a television is a damn site less compelling than 4 people jumping around with remotes to Wii Sports infront of the television. Nintendo aren't going to abandon what makes console gaming work, and what they did so well with the Wii.
Whatever new idea they have, it is far more likely to build on their strengths rather than throw a lot of the strengths out the window. Also one of the main things they will want to fix with the Wii is its narrow content, another reason to put the emphasis on the power of the console rather than that divert resources to a very expensive and fragile way of interacting with it.