For the "tablet" issue, at least relating to display sizes (then again, even from this thread it's quite obvious that there is no consensus over what actually constitutes a "tablet"):

As said for instance in the current human interface guidelines version ("You must always keep in mind not only the small size of screens where your application will be displayed but also how much they will vary."), and as said consistently: there are plans to support multiple different screen sizes, i.e. provide UI scalability to certain extents. A good software platform is able to do that.

Naturally we don't want to do that just for fun.

That's for the Maemo side. But please don't expect anybody with any real information from Nokia to comment prematurely on upcoming future devices.