Most likely. Vast majority of so called "leaks" are just a LARP bullshit and new class was widely anticipated because it fell right in the historical cycle where new class would have been introduced.
I do hope and expect 10.0 to introduce a new class and I hope it will be a ranged damage dealer too. Who knows, the whole Sylv flip flop thing might lead to Sylvanas' Dark Rangers joining players and there are "Alliance" ones there too.
Now people may say "but Hunters", true, however it's just like melee really. Existence of Warriors did not somehow prevent Death Knights. This could be pretty much same thing - a ranged bow user without pets and instead with darkness, shadows and undeath themed stuff.