I think this could be fun if it was done for flavor and not power and treated more like a class skin than an actual build.
For example, we take a warrior and blend him with a mage and "replace" the keystone abilities for the class with appropriately flavored ones. So when he leaps or charges its just the blink animation that plays. Thunderclap is instead arcane explosion, ect. Ect.
While it would be fun to do an actual power progression, I don't believe it would be handled well by Blizz atm.