I seen a cool hunter spell damage build on private where they would hot swap gear with +spell dmg and use explosive traps / sapper charges as some weird hunter spell damage aoe build? Not sure on the specifics and doubt it would translate well into Classic. I also seen a spell damage rogue build that was being theorycrafted with fiery enchants, im not sure how that ever turned out. Needless to say, neither of these things rewrote the meta. A rogue being a rogue will likely perform better than a rogue trying to be a mage due to the itemization on rogue items. This is true for almost all classes.
"Will we be seeing new metas, or will history just repeat itself?" The meta constantly evolves. This will never ever stop, in any game, ever. However, most of the top tier performing specs will remain the same. You may find some neat niche stuff that we havent seen, but it wont be some game breaking discovery that millions and millions of users have missed throughout 15 years of play. I'm always interested in new ideas or new ways to combine odd item interactions, however I dont forsee that the meta will be rewritten in Classic. I suspect there will be a constant and sublte shift of the meta forever but that we have a pretty firm grasp on what to expect.