Initially I thought the Evoker would probably be too similar to a Mage, and it probably will be somewhat similar. But looking at concept art like that of Dragoncaller Alanna, I got to say, I can see the class coming together.
When you look at the picture, you can see the dragon she is summoning is actually one made of fire. The idea of summoning dragons was a bit too weird to me, but if they are dragons made of fire or ice, that charge at the enemy as part of an attack, similar to the Phoenix spell from Mages, I can see that as a new class.
Also the lore apparently has now been retconned to dragons being elementals. With that, it makes even more sense, that an Evoker would use elemental magic and call on elemental dragons.