Actually, this "remix" has already happened.
For the record, the Black Rebellion compilation was originally released back in 2008 and Zero Requiem came out in 2009. In other words, I assume this is simply a re-release of those two compilations with a different set of covers and not an entirely new product.
You can find both of them on Amazon Japan or anywhere else without too much effort. They're not particularly worth watching though, let alone buying, but that's just my opinion.
The only good news here, at least from my point of view, is that Code Geass Gaiden
is still going to happen...but probably not before 2012. Otherwise, they wouldn't even bother to speak about doing anything "in preparation" for it as late as September 2011.