Although there wasn't plain sampling+cut&paste involved, those examples are still a product of human voice actors who gave consent for their voice to be used as the source. Now I wonder what happens a few years from now should someone produce a new song with a singer who sounds exactly say like Elvis, same tone, same style, although Elvis isn't mentioned anywhere. Elvis is dead, so it can't be him, and the track wouldn't be a copy of anything Elvis sang during his life. Also demonstrating that Elvis voice has been used to train an AI would be hard (assuming the voice wasn't created entirely from scratch). A lawsuit from the Elvis Estate would probably follow, but on what grounds? We might see some deep modifications to copyright/trademark laws when this happens.