When a new interface comes on the scene, and assuming that people won't add more hours to their computer time, it can't help but cannibalize time spent on other interfaces. Halfway through that process it's really easy to project that line until it is 100% of all interface usage anywhere.
But here in 2018, we really ought to all have a pretty clear idea of why touch screens are in no danger of displacing mice and keyboards 100%. It's pretty obviously not going to happen, and not particularly mysterious why.
In other news, phone-based gaming is also obviously not going to kill dedicated consoles anytime soon.
In other, other news, see also why touch screens need not fear being entirely replaced by voice-based computer usage. In much the same way that touch screens didn't, can't, and won't completely replace other higher-bandwidth ways of interacting with computers, voice has those same problems w.r.t. touchscreens even more so. You can get a nice boost on the bandwidth in the computer input direction, but you get annihilated on the bandwidth coming back out compared to a screen. There is no other computer IO mechanism that so thoroughly lacks bandwidth back to the human as a voice interface, short of a plain flashing light on a physical console. (Which, actually, if the human knows Morse code or something, could damn near keep up with the voice interface on the bandwidth front. That's how bad voice interfaces are on the output bandwidth.)
But here in 2018, we really ought to all have a pretty clear idea of why touch screens are in no danger of displacing mice and keyboards 100%. It's pretty obviously not going to happen, and not particularly mysterious why.
In other news, phone-based gaming is also obviously not going to kill dedicated consoles anytime soon.
In other, other news, see also why touch screens need not fear being entirely replaced by voice-based computer usage. In much the same way that touch screens didn't, can't, and won't completely replace other higher-bandwidth ways of interacting with computers, voice has those same problems w.r.t. touchscreens even more so. You can get a nice boost on the bandwidth in the computer input direction, but you get annihilated on the bandwidth coming back out compared to a screen. There is no other computer IO mechanism that so thoroughly lacks bandwidth back to the human as a voice interface, short of a plain flashing light on a physical console. (Which, actually, if the human knows Morse code or something, could damn near keep up with the voice interface on the bandwidth front. That's how bad voice interfaces are on the output bandwidth.)