My skepticism is about the cost in dev time. This looks like the biggest balance and design project in the new expansion. Why is it necessary?
The new talents may end up being a perfectly fine system in their own right, but what was wrong with the old system that justifies spending this time on a rework? Getting this means we don't get something else that they could do instead. As far as I can tell the current system wasn't causing any complaints, so the unnecessary rework could end up being project mismanagement.
Especially if it turns out the new system is mediocre and Blizz is left holding the ball.