Sha of Happiness, obviously.
My favorite Blizzcon in-game item will always be the murloc suit.. it'll probably be another murloc pet.
The Book of Ghost Crab:
And he led them out until [they were] over against Orgrimmar: and he lifted up his hands, and buffed their classes. And it came to pass, while he buffed their classes, he parted from them, and was carried up into the Emerald Dream. And they worshipped him, and returned to the General Forums with great joy.
A Glyph for Priests where your Spirit Of Redemption looks like a Murloc.
so the most likely one would be a wow themed murloc and since the main two expansion ideas is burning legion or naga/old gods it would likely look like something thematically similar to whichever comes out.
unless they go with a blizzards all star themed one or a titan themed one but i dont think titans ready yet to be announced.
"I was a normal baby for 30 seconds, then ninjas stole my mamma" - Deadpool