Here's to hoping there's some added depth to how strong you can make your character through skill trees. There really isn't much separating each class except for supers, so to add other skills for each class would be great. They could really benefit from having a Paragon level-esque system where you continue leveling after 40 but use it to add on to preexisting stats like speed for hunters, toughness for titans, and intelligence for warlocks. Stats like that won't probably be added through TTK, but hopefully somewhere down the line would be nice.