If the WWE were planning on bringing back Viscera, we'd probably have heard about it by now. I personally have my own theories as to who's behind the notes. In truth, I've narrowed it down to two in my own mind.
R-Truth comes to mind first. If it were him, it would be to mess with their minds as a preparation for some other form of attack. Perhaps Truth himself has his eyes set on the Million Dollar Championship.
The other person who might just be behind this is...The Great Khali. I'm serious about this one. We all remember the rather stupid yet admittedly amusing bits he used to do for the Khali Kiss-Cam and he's still billing himself as the Punjabi playboy. In addition, there was that bit where he flashed that picture of his "girlfriend" and eventually admitted to her being unattractive and he went off with the Bella twins. Could it be, perhaps, that they've encouraged the Khali character to go for the more, shall we say, media-encouraged sort of beauty and who better exemplifies that than Maryse?
That's only if Maryse is the target, however. If it's Debiase, then Goldust would be the most likely of all.
There is one other possibility. Supposing, just supposing, the unknown GM is female. If such is the case, this could be an additional factor to that story line. We'll never know until it's revealed.