I remember back in the 90s N64 magazines were always posting rumors about the "Dolphin" console that Nintendo was supposed to be developing, which eventually became the Gamecube. Nintendo also was more open back then, with their famous Mario 128 tech demo for example. Also the Nintendo DD rumors were huge as well, which turned out to be a big failure and never released outside of Japan.

I mean, they kind of have to do that, or else you get the Osborne Effect where everyone just waits for the new version, and your business suffers.

ETA: also, source? They usually say they won't comment, or that there's always something new in development at all times. Don't they?