I don't know how a Bleach/Fairy Tail merge would work. I stopped reading Fairy Tail aeons ago, but I read the thread once every blue moon to see if there's a cataclysmically memorable moment on it BUT it seems lately most chapters are received with a "pretty decent" comment by most readers/forum users (the ones that still read that manga, of course), so I think maybe Fairy Tail won't be able to compete with Kubo's trully exceptional moments of extreme stupidity.
In fact, even at its lowest moments (and by God has FT had incredibly terrible moments to spare), FT's whole "thing" is that's bland and mediocre and uninspired, not head-scratchingly, impossibly stupid like Naruto and Bleach can be when Kishi and Kubo feel inspired enough. It also never had even 1/10th of the quality Naruto and Bleach DID have once upon a time; even at its highest, Fairy Tail is just ok/decent/mildly entertaining.
So, yeah, I don't think it deserves a merge with such mammoth of inconsistency and amusing terribleness (with the occasional "shit, that was good!" moment) that Bleach is.
(Plus, I might be wrong, but the Fairy Tail thread actually has. . .not that many people commenting on it anymore, whereas Bleach/Naruto has a pretty sizeable chunk of the forum comming at it, teeth bared, on a weekly basis).