If the well for possible 360 BC releases was drying up due to licensing and other factors, (and I'm not saying it is), I'd be totally fine with BC X enhancements released on weeks when they don't have any new games to add.
I'm left wondering how hard it is to X enhance these BC games. If it were just Halo and Gears then I might assume it takes a good bit of effort but the fact that a game like Mirror's Edge got enhanced makes me wonder since I doubt that a ton of work went into enhancing that game.
From what I gather, a lot of the games already ran uncapped and had higher res textures available but downsampled to fit the 360. So they might not take too much work to get them using their available assets and coding.