every expansion has seen murlocs featured in some way whether it be murlocs themselves or a subspecies/evolution of them
vanilla had normal murlocs
bc had murlocs released into the wilds of outland
wrath had the gorlocs a smarter more calmer sub species of the murlocs that worship the titans and love shiny things
cata had deepseas murlocs
mists has the jinyu a hyper evolved version of the murlocs that evolved in pandaria.
so what do you think murlocs will be doing in 6.0? will we see a return of the classics or will there be a new form of murloc (fel murlocs? narlocks? murloc bombadiers?)