In a week we will be able to install Wrath of the Lich King and start leveling up from 70 to 80. But already since patch 3.0.2 the level 71 to 80 new spells and abilities are visible on the class trainers, if you set your filter to "show unavailable". So yesterday I had a look with my three level 70 characters to check what new spells and abilities await me. And the answer was: Nearly none. The number of really new spells and abilities is tiny, most of what the class trainers have on offer is higher ranks of already existing spells. That is somewhat disappointing, but understandable.
The problem is that Blizzard can't simply add a one new spell or ability per new level to the game, because then quickly you would have far too many hotkey buttons. I'm already using 5 hotbars with 12 spells, abilities, or items on each of my characters. And those characters who have different stances have even more, because the basic hotkey bar changes when you change stance. Blizzard did generally a good job on making well recognizable icons, but at some point there are simply too many of them. Especially when some of them aren't used very often, you have problems finding the button in a hurry when you actually need it.
And then of course every class has a specific role, and it wouldn't be a good idea to give a class new spells and abilities that used to be reserved for another class. But if you say "no big dots for a mage, because dots are for warlocks", then what new spell *can* you invent for a fire mage? There are only so many ways you can make a spell deal fire damage, and mages already have all of them. What new way to heal do you want to add to a holy priest?
Unless the combat system is completely reworked (which I wouldn't recommend, as it wasn't exactly a success with SWG's NGE), I don't see how Blizzard can add lots of new spells and abilities in this and future expansions. We'd only end up with more buttons doing more or less the same.
What is possible, and there are already signs of it, is the use of more combinations of spells and abilities, especially via talents. My frost mage can now sometimes cast a fireball for free and instant, or get a "frozen fingers" effect with which his next spells treat the opponent as if he was frozen, which gives an added effect to spells like ice lance. My protection warrior can sometimes get a shield slam for free, or if he would spec arms sometimes use execute in the middle of the combat instead of just at the end. Random bonus effects like these break up the monotony of combat a bit. Just right now the standard UI of WoW isn't all that great in informing you about them, but I managed to configure SCT to give me very visible warnings every time I have the option to use such a combo.
So while lets say my frost mage isn't really gaining many really new spells in Wrath of the Lich King, at least he isn't just using frostbolt-frostbolt-frostbolt-frost nova-frostbolt any more. What he got in new abilities was mostly patched in by the changes to the talents tree in patch 3.0.2., the level 71 to 80 spells won't bring much newness. The one thing that is a bit annoying about that is that there are no class trainers in Northrend, just like there were no class trainers in Outlands, and every level you have to travel back to old Azeroth, just to get a boring added rank to some old spell, and then travel back to Northrend to level up again. As Dalaran won't be immediately accessible, like Shattrath was, that'll be even more annoying for the first couple of levels. At least my mage can teleport, my priest and warrior will be more annoyed by having to do trips like that every level.