I don't have the source handy, but I'm pretty sure either Iwata or Miyamoto said in an early Super Mario 3D World interview (back when we were all being skeptical about it) that they considered it a seperate series, and that the next game in the 64/Sunshine/Galaxy series was in development seperately (probably small scale prototyping).
The successor to Galaxy will come.
Errr..
If I'm wrong I'm wrong, but I'm pretty sure all that was said was something like "Hmmm, I'm sure we could do something with the Galaxy games again. We'll look into it, but we wanted to make something new (3D World)."
It really doesn't confirm anything (kind of a throw away comment), and I wouldn't be surprised if a lot of SMG2's unused or scrapped ideas went into the development of both 3D Land and 3D World.
For EAD Tokyo there is a clear distinction between the style of the post-Sunshine games and the pre-Galaxy games; Galaxy was sort of the first step into reviving the classic style of platforming while bringing it into a new era, I'm not entirely sure where you're getting the idea that they lump those games together with Sunshine and 64.
Hell, I'm not even sure they think of 64 and Sunshine being the same "series"...that's kind of just a fan construct.