It's not a huge surprise: first smartphones and then tablets have done away with the need for a PC to carry out many -- perhaps even most -- basic computing tasks such as email or web browsing.
And PC makers were far, far too slow to respond to the threat to their market, only recently finally coming up with the two-in-one devices and hybrid tablet-PC products which have created a certain amount of interest among consumers and businesses.
Now, as the chart below shows, there's still a lot of PCs out there - and there will continue to be, too. But rather than being something that might get upgraded every three years, PC replacement cycles are slowing as many applications now run in the cloud, which makes local processing power less relevant to hardware owners. And it's likely PCs are being used less too, even if there is more than a billion of them out there.
That doesn't mean it's the end for the PC, however: gamers will keep buying and building super-powerful PCs for one, and business will be another big hold out.
But the direction of the trend is pretty clear: the PC is no longer the centre of our computing experience, but one device among many, and PC makers and users need to adjust to that.
It's not just about new devices being used instead of, and as well as, PCs, but also that these other devices have very different user interfaces: input has moved from the keyboard and mouse of the PC, to touch for smartphone and tablets and now, perhaps, it looks like the next big thing could be voice.
Work on getting computers to understand human conversation -- and to be able to talk themselves -- goes back decades, as our in-depth history of the development of speech technologies published this week shows. It looks like we are reaching an inflexion point: speech is now becoming a mainstream method of communicating with our devices.
Just last week Amazon's sleeper hit, the Amazon Echo, went on sale outside of the US where it has already sold around three million of the voice-activated smart speakers. What's interesting is that the Echo is entirely voice-controlled: at the launch, Amazon detailed some of the tough computing problems it had to solve to make the device work.
Voice is a far more natural interface for us than using a keyboard and mouse. So, as neural networks and cloud computing make it much easier for us to communicate with computers, it's highly likely we'll see these speech technologies used far more widely. It's obvious that speech is the best interface for wearables that are too small for a keyboard, or for in-car systems where the driver cannot be distracted. If devices like the Echo succeed, voice could very quickly become a dominant user interface for many devices.
So what does this all mean for the future of the office PC? Probably the biggest reason the PC has managed to survive so long is its ability to reinvent itself. The beige box of the 90s bears little resemblance to the sleek creatures of today. Perhaps the next thing the PC is going to shed is the keyboard as speech becomes the standard form of input.
Offices used to be filled with the noise of clattering typewriters until it was replaced with the quieter tap of the keyboard. Perhaps they're going to get noiser again, filled with the sound of us talking to our PCs instead.
ZDNET MONDAY MORNING OPENER
The Monday Morning Opener is our opening salvo for the week in tech. Since we run a global site, this editorial publishes on Monday at 8:00am AEST in Sydney, Australia, which is 6:00pm Eastern Time on Sunday in the US. It is written by a member of ZDNet's global editorial board, which is comprised of our lead editors across Asia, Australia, Europe, and the US.