We know that all Hoenn Pokemon are transferable to gen 5, so I wouldn't say that giving some Hoenn legendaries in B2/W2 means no remakes in gen 5. Game Freak just wanted to put some previous gens' legendaries in B2/W2, so they put Hoenn and Sinnoh ones, because they are the newest and weren't featured so many times. We should notice that the most important legendaries for Hoenn storyline (Weather Trio) are not included in B2/W2. I think that Jirachi and Deoxys are not included either, because I feel they will have events in R/S remakes.
Seeing how B2/W2 don't have following Pokemon feature and no special touch screen features like in HG/SS, I think those things could be saved for R/S remakes, just like they were saved for HG/SS.
There's another thing I want to point out, you will probably say it's not hint at all, but there it is - I find it very weird that Hoenn Gym Leader remix in B2/W2 doesn't have any trumpets. Especially when Kanto and Sinnoh remixes have them. It's suspicious because trumpets are the most used instruments in Hoenn tracks. Looks like Game Freak had very good reason to avoid trumpets in B2/W2 remix of Hoenn Gym Leader. Probably they are saving version with trumpets for R/S remakes.
Those Hoenn Trainer battle and Rustboro remixes in B2/W2 are very suspicious too, and could be hinting to R/S remakes (assuming they really are hidden in B2/W2, they could be just fan-made rumors).