The biggest barrier to Windows 10 success is still Windows 7

This year's CES saw plenty of shiny new Windows 10 devices on display, from the acrobat Lenovo Yoga through to HP's all-in-one Sprout Pro.

Hardware like this will certainly boost the fortunes of Windows 10. Sleek new designs and form factors, and the rise of two-in-one devices like the Surface Pro that can function both as a PC and a tablet, are giving consumers and businesses a reason to invest in Microsoft's latest operating system.

And Windows 10 has made some decent inroads thus far: it now accounts for somewhere around a quarter of PCs accessing the internet as measured by NetMarketShare.

All data like this needs to be looked at in terms of trends rather than details, of course, but in December 2016 - the most current data available, Windows 7 stood at 48 percent, Windows 10 had 24 percent, Windows 8.1 held seven percent, Windows XP nine percent, and Windows 8 had just two percent.

Contrast that with June 2015, just before Windows 10 arrived. Windows 7 stood at 61 percent, Windows 8.1 at 13 percent, Windows XP had 12 percent and Windows 8 just three percent.

A few obvious points leap out.

First, Windows XP usage hasn't changed very much at all as a result of the arrival of Windows 10. That's hardly surprising: Windows XP wasn't part of the free consumer upgrade programme that Microsoft offered. Windows XP is long, long past its sell-by date, and most of the hardware running XP is probably so old that is can't be upgraded anyway. If users are happy running such an antique and insecure operating system they'll probably keep using it until the hardware gives up or the Sun expands to finally vapourise the Earth, whichever is sooner.

Second, Microsoft did a good job encouraging people to move away from Windows 8. Perhaps they didn't need much encouraging, considering the reception that Windows 8 got, but it's all but vanished. For Windows 8.1 its (unsurprisingly) is a similar story and usage has fallen rapidly, which presumably means many users have been happy to take their (largely) free upgrade to Windows 10.

But what about Windows 7? This is the big one, of course. Usage has declined according to the NetMarketShare data - from 61 percent to 48 percent over 18 months, which looks at first glance like a rapid decline.

But the big question for Microsoft is whether that erosion of Windows 7 usage will continue.

Looking at the numbers more carefully, most of the drop in Windows 7 usage came in the first year that Windows 10 was available: since April 2016 Windows 7 usage has stayed pretty stable.

That's likely because most of the switchers were consumers. More cautious types and businesses in particular have held fire.

In Windows 7, Microsoft built a good product that companies like. It's now tried and tested, works with their existing infrastructure and their users are confident using it. And they worry about how big a leap it is to Windows 10, though more will no doubt consider the upgrade as Windows 7 heads towards the end of its lifecycle (Microsoft's extended support, which included security updates, ends in January 2020).

Unless Microsoft finds a compelling set of reasons to encourage upgrades, it risks Windows 7 going the same way as Windows XP and becoming an operating system that just won't die. That could become a real headache for Microsoft if it happens.

Microsoft, of course, would very much like as many users as possible of Windows 10, if only to help ignite the app ecosystem it is trying to build. Much hangs on the reception of the Windows 10 Anniversary Update which some think will be the final push that starts enterprise rollouts. And so it is no surprise that one Microsoft exec has already warned that Windows 7 "does not meet the requirements of modern technology, nor the high security requirements of IT department."

Microsoft has big ambitions for Windows 10, even if it has admitted it won't now hit its own target of one billion Windows 10 devices by 2018. Just when it does hit that target will depend greatly on persuading Windows 7 fans to upgrade sooner, rather than later - or not at all.

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 8am AEST in Sydney, Australia, which is 6pm 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.

Previously on Monday Morning Opener:

• Apple's iPhone turns 10: Here's how the device impacted business, work
• The 4 tech trends that will shape 2017
• The 5 biggest tech trends of 2016: ZDNet editors sound off
• The biggest threat to artificial intelligence: Human stupidity
• Cloud compute pricing bakeoff: Google vs. AWS vs. Microsoft Azure
• Can Trump stop the automation revolution and save US jobs?
• The PC is having its mid-life crisis, just a little bit early
• Apple to revive the Macbook, as iPad falters and IBM launches biggest Mac rollout ever