While adding branches to the sides would make the talent tree to bloated, making a feature that could “remove” one of the tree paths and replace it with another in its slot could work, that would however mean that every new path would have to have the same layout in the potential slot it would go in, example they would add three new paths for the left, middle and the right existing paths for each class.
That or just keep adding things at the bottom of the tree and give us more points.