so in wod there are no new spells and abilities not to clutter up action bars even more. instead we get upgrades to our existing abilities enhancing them.
however i remember when blizz said we get one every level, even watched tradechat (or whatever shes called) video on youtube yday and it confirmed that i wasnt wrong. im currently lvl 96 on dk and for both of my specs ive got 3 enhacements (for each spec), so thats 1 ability enhancement every 2 levels.
There is a list of all the abilities that get enhanced, for each class, you get a random one, or two, on every two levels.
And then on 100, you get a talent.
originally it was one every level, but most of them were just static upgrades like "X does X% more damage" and those got removed/just baked in.
as for why we aren't getting new spells in general. the 100 talents kind of replaced that, as well as their focus on removing abilities this expac instead of adding them