No, it's not. Balance Druid has three "old" talents brought back and one completely new one. The rest is in the game right at this moment. There are 34 talents in the Balance tree of which four are not recent as of now. And it's not like it matters much anyway. It's the same for the other specs. The amount of old or completely new talents is negligible.
Tuning in Shadowlands where there were several progression systems was so much more than the small amount of tuning these talent trees require. Just look at them. We don't have a dedicated borrowed power system at max level. Tuning for Dragonflight will be one of their easiest jobs by how shallow the talent trees are in their respective design.
A system that was build on Talents -> Covenant skills -> Soulbinds / Conduits -> Legendaries required tons of tuning because of the dependencies of all the stuff. In Dragonflight none of this exists anymore. It's most likely the easiest time for the combat team since WoD, because all Legion, BfA and Shadowlands had way more complex and intricate systems to tune and balance.