Well, this season it was not hard to guess, but i think next season will be a little bit harder.
If nothing new is found i see the WD as the only trash killer (hammerdin should still not do enough damage compared to WD?!)
and the necro is the unbeatable bosskiller. Since the bugs will be fixed it will even be stronger (or at least less boss fishing) for 130+.
But i did not test anything and this is just speculation and i am very curious if there will be new combinations and i hope so.