Will voice kill the keyboard. No. Will the way we interact with Emacs, and computers in general, change drastically? No.
Star Trek has a mythical AI/computer that responds to voice commands and interacts with you to clarify or note other work that may pertain to what you wanted. Evidently the interface is so ubiquitous that Scotty talks to a mouse noting it's "quaint" to need to push it and type on a keyboard to interact with a computer.
But if we watch the bridge of any Star Trek show people aren't talking the whole time. They're tapping screens to get the computer to do things for them. Theoretically the captain could tell the ship where he wants to go and let the computer do it, but he issues a command and then someone types in the needed commands to the ship so it goes in the expected direction.
I work at home in a solo office space. I could talk to my computer and it would disturb no one, except me. I'd be unable to listen to music on my stereo at the same time just in case the computer couldn't understand my words versus the song.
I don't think keyboards are going anywhere any time soon. They provide an unambiguous interface to your computer that doesn't disturb others. I think that those loving Emacs interactions like they use it will continue to do so as they do now because it's the most efficient way to control the Emacs interface.