Microsoft expected to accelerate patch schedule with Windows 10
However, how often Microsoft will release new branches and how long it will support old ones is still unclear.
"Nobody knows how long these branches will last," said Chris Goettl, product manager at Shavlik Technologies, which focuses on patch management.
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Meanwhile, Windows 7 is currently scheduled to be supported until 2020.
"I anticipate that there will be a lot of businesses who will stay on windows 7 for a long time," said Goettl.
Consumers -- and companies attacked by botnets living on unpatched consumer machines -- will be the big winners here, he said.
"Consumers will be on what Microsoft is calling the 'current branch'," he said. They'll get the latest releases and patches as they come out.
"For the consumer space, I see this as a very good thing," he said. "From a features perspective, they expect that if there's something new and cool that they're going to get it as soon as possible. And from a security perspective, it's even more important. A home user doesn't understand the security implications of delaying updating the software."
Large companies, with enterprise licenses of Windows 10, will get the most choice, can stay on older branches longer, and can choose to only install security updates, he said.
Small and midsize companies running the "professional" version of Windows will have the least choice.
"You can take releases as they come, or you can go one branch older than current so you can test out the new features," he said. They won't be able to stay on older branches, however.
The forced upgrade schedule may cause some companies to upgrade their licenses to the enterprise level -- if they upgrade to Windows 10 at all.
Other companies that may choose to stick with Windows 7 are those that are heavily regulated. PCI and HIPAA compliance requirements, for example, make it difficult to quickly upgrade operating systems.
And companies that have proprietary apps or legacy applications may also delay switching, he said.
"Microsoft has put out an aggressive goal to get a billion devices on windows 10," he said. "But I would tell companies to start a proof of concept, vet things out. I would question exactly whether that free upgrade is worth it or not right now."
One potential driver for change is Microsoft's focus on having a single operating system for all devices -- desktops, laptops, tablets and phones.
But with a 5 percent market penetration in the tablet space -- and a smartphone market share half as big -- it's unclear how much of a pent-up demand there is for a single operating system to rule them all.
"They're doing interesting things to consolidate the marketplace," Goettle said. "But the Windows mobile phone is not getting anywhere near the adoption rate that anyone has any huge expectations there."