I'm having a hell of a time finding the specific post, but I could have sworn hmxhenry mentioned the possibility of more artist teasing after Blitz was out of the way.
Also, sidenote: It was also mentioned that there were a "few" things in the works for the Rock Band anniversary. The mega sale was obviously the big one...but, anything else to look forward to? Beyond giveaways, I mean? Perhaps some sort of a specialized DLC pack (I wish)?