The Beatles: Rock Band came out 9/9/09, a day where Rock Band 3, only was speculation, and keyboard was'nt known by the public. TB:RB came out with a lot of great songs, but some fans noticed, that major hits like Strawberry Fields Forever, Let It Be, Hey Jude, Lady Madonna and so on was missing, and that Rubber Soul, Sgt. Pepper and Abbey Road would come out as DLC.
The goal for HMX was release these 3 albums, while TB:RB hype still was high, after the release, and before Keyboard was announced. Noticed that these 3 albums does'nt include the major hits? Rubber Soul had some good hits on it, but keyboard/piano did'nt have much influence on the majority of songs, so it was perfect to release. Sgt. Pepper had a few songs with piano, but not the big sellers. Lovely Rita and Fixing A Hole is great songs, but not on the same level as Lady Madoona and Let It Be. Abbey Road contained the famous medley, which has a few keyboard parts, but nothing big. Maxwell's Silver Hammer was the only song with keyboard, but i guess it would be to borring either way.
So what am i trying to tell you? Im trying to tell you, that TB:RB export is not quite impossible, and the timing for new DLC, with a keyboard patch is possible.
My theory goes, that before the planning of which songs that should be included, they were looking at the future and the keyboard feature. So why would they release big piano songs, with no piano, when people would know that keyboard will be avaible.
It seems likely, that the great songs with piano, and a majority of the Revolver and MMT songs would be perfect to release.
I have 3 options.. actually 4, with what that could happen.
Option 1: As a teaser for Rock Band 3, they would put the keyboard up for sale in september, and on the same time release TB:RB DLC. And they would have known when they made the game, that keyboard would be a part of TB:RB, so it was already build into the game from the start.
Option 2: They will see how well the keyboard hardware sells, and how popular it is, and then release TB:RB DLC in october, late november.
Option 3: Keyboard will not be supported, but to give RB fans something to hold on to, before Rock Band 3, they will release
Option 4: Nothing will happen, and the waiting will continue, unless they tell us, that they left TB:RB.