Depending on the actual terms of the contract, I don't see how this is terribly different than getting a sound-a-like voice actor to do an impression of that rendition of the character. Would the estate still be making money on that voice's use? Would it augment another human actor's voice in the same way that they had to have an actual human when they filmed the Princess Leia shot for Rogue One?
Seems like the devil (or not) is in the details of how this tech would be used.