What are you talking about?! I already said the existing incarnate branches would not be changed.
As far as Hard Mode goes, that would be a dev call as to whether it counts as incarnate powers were a factor in their design. And even if Advanced Mode content didn't count and we could not use the not made 4 branches of incarnate powers, we still would not be losing anything. And if Advanced Mode content did allow for the other 4 branches, Advanced Mode content is not designed with those powers in mind, so Advanced Mode content would no longer be "tuned pretty well" because now we would have even more power to bring to bear in content that is not designed for it. And if the other 4 branches are stronger than the current 6, then you know full well the weakest of the 6 would be dropped in favor of the new 4, so any balance Advanced Mode content has for incarnate powers would still be out the window because players would only be using the most powerful branches. And if the other 4 branches are not stronger, then odds are the current 6 would still be the ones chosen.