Playing TBRB in my house has had an interesting effect on my 2 boys. My youngest (7) asked if he could take piano lessons at the start of the summer so he can learn music, and is saving his allowance and tooth fairy money to buy himself a drum set.
My oldest (8) went to his grandmother and made a deal with her. If he saves up enough money for 2 months of guitar lessons, she'd pay for an electric guitar starter pack. He just bought a block of 10 one hour group lessons at the community centre with his Birthday money.
So we went into the store to look for a starter pack for him. In talking to the owner apparently he's been doing a brisk sale in starter packs for kids thanks to RB in general and he says THRB specifically.
"The parents with young kids have been coming in this summer, buying these starter guitars because their kids loved playing Beatles Rockband so much they all want to be a Beatle." He told me.
And he's had a lot of grown ups and teens coming in buying Beatles sheet music and asking about their instruments. He's also been selling more Beatles picks and straps too.
Just an anecdote from one store, but a year on it seems the game is still having an effect.