Also, the fact that a Rustboro remix was programmed into B2W2 but is not used ANYWHERE in the game could very well be some sort of evidence too. Although, I think I remember that they put a remix of Suicine's battle music in FRLG and it meant nothing but who knows.
The hints are quite subtle, because you can't be 100% sure as to whether they thought of them as hints or not when putting them in but I'd say the ones you mentioned are very interesting and its likely that they could be hints.
There are even more things in B2/W2 resembling Hoenn. Going through underwater to get to final gym, new Champion who used to be Gym Leader and left his/her mentor as Gym Leader, crisis and music change caused by actions of mascot Pokemon - Kyurem's ice did that in Opelucid, the same like Kyogre's/Groudon's powers in east Hoenn. Hidden Hollows in B2/W2 resemble Secret Bases in R/S/E.
Of course all those things can be said to be coincidences, but there are so many of them that it's hard to believe Game Freak made them all without thinking about remaking R/S/E.