All they said that was, and I quote verbatim, "This is not JUST another Rock Band expansion". That "Just" in there seems to imply that it is an expansion for Rock Band, but it will also be so much more than that.
If it wasn't to be associated with Rock Band at all, then they would have said straight out "This is NOT a Rock Band title". See where the difference lies? The guys making these announcements are quite skilled in the art of PR, they know what words they are choosing.
Only time will tell though, all the conjecture in the world won't solve this right now. I'm still convinced that there will be an export code, but there will be much more on the disc. Maybe you'll have to go through the career mode to get the code? I don't know yet, we'll see.