I was there for about a decade and every year he'd have some new take on how he'd take down the keyboard. I eventually heard every argument and strategy against the keyboard you can come up with - the QWERTY layout is over a century old, surely we can do better now. We have touchscreens/voice input/etc., surely we can do better now. Keyboards lead to RSI, surely we can come up with input mechanisms that don't cause RSI. If we design an input mechanism that works really well for children, then they'll grow up not wanting to use keyboards, and that's how we kill the keyboard. Etc etc.
Every time his team would come up with some wacky input demos that were certainly interesting from an academic HCI point of view, and were theoretically so much better than a keyboard on a key dimension or two... but when you actually used them, they sucked way more than a keyboard.
My takeaway from that as an interface designer is that you have to be descriptivist, not prescriptivist, when it comes to interfaces. If people are using something, it's usually not because they're idiots who don't know any better or who haven't seen the Truth, it's because it works for them.
I think the keyboard is here to stay, just as touchscreens are here to stay and yes, even voice input is here to stay. People do lots of different things with computers, it makes sense that we'd have all these different modalities to do these things. Pro video editors want keyboard shortcuts, not voice commands. Illustrators want to draw on touch screens with styluses, not a mouse. People rushing on their way to work with a kid in tow want to quickly dictate a voice message, not type.
The last thing I'll add is that it's also super important, when you're designing interfaces, to actually design prototypes people can try and use to do things. I've encountered way too many "interface designers" in my career who are actually video editors (whether they realize it or not). They'll come up with really slick demo videos that look super cool, but make no sense as an interface because "looking cool in video form" and "being a good interface to use" are just 2 completely different things. This is why all those scifi movies and video commercials should not be used as starting points for interface design.