I've run Microsoft estates for most of my career, and the last decade compressed more change into that stack than the twenty years before it. If you'd shown my 2016 self what "a Microsoft shop" would mean in 2026, most of the words would have been unfamiliar. Here's the journey, and the one thing that stayed constant through all of it.
1. 2016: the on-prem world
Ten years ago, running Microsoft IT meant physical and virtual servers you owned: Active Directory as the heart of identity, Exchange in a server room, Windows Server everywhere, a firewall at the edge. The skills were the classic MCSE-track disciplines — directory design, Exchange, storage, networking. The mental model was a castle: a hard perimeter around a soft, trusted interior. It worked, and I spent years getting good at it.
2. The cloud pivot
Then the centre of gravity moved. Office 365 turned into Microsoft 365 and swallowed email, files and collaboration. Azure went from a curiosity to the default place new workloads landed. Crucially, identity followed: on-prem Active Directory grew a cloud twin — Azure AD, now Entra ID — and hybrid identity became the reality most of us actually ran. The castle got a second home in the cloud, and the walls between them got complicated.
This wasn't a lift-and-shift you did in a weekend. It was years of migrations, co-existence, and unlearning. The engineers who thrived treated it as a new set of fundamentals to learn, not a threat to the old ones.
3. The certification earthquake (2018–2021)
Microsoft made the shift official — and painful — in its certifications. From September 2018 it pivoted hard to role-based certification, adding dozens of new credentials across Azure, Modern Workplace and Business Applications. Then, on 31 January 2021, it retired MCSA, MCSD and MCSE entirely. A generation of engineers watched the letters they'd built careers on become historical footnotes.
The MCSE retirement felt personal to a lot of us. But the deeper lesson was liberating: certifications certify a moment; the underlying models — identity, directory, networking — carried straight over into the cloud world. Platforms expire. Understanding compounds.
I hold the older infrastructure track and the newer Microsoft 365 and security credentials, and I don't see them as competing. The old ones taught me how directory and messaging really work; the new ones taught me how those same ideas live in the cloud.
4. Identity becomes the perimeter
The most important change of the decade is easy to miss because it happened gradually. The perimeter dissolved. Once your apps and your people were both outside the building, the firewall stopped being the boundary and identity became it. Multi-factor authentication went from optional to mandatory. Conditional access — decisions based on user, device, location and risk — became where a modern Microsoft estate's security actually lives. "Zero trust" stopped being a slogan and became the operating model.
5. The AI layer arrives
And now, the newest stratum. Copilot arrived across Microsoft 365 and Azure, and in 2026 it has become something you administer rather than just enable — agents with their own identities, a control plane to govern them, security tooling that itself runs on AI. It's genuinely powerful, and it rests entirely on the identity and data-governance work of the previous decade. An AI assistant is only as safe as the permissions model underneath it, which means every shortcut anyone took on that model over ten years is now, suddenly, live.
6. The through-line
Ten years, and the product names churned almost completely — Office 365 to Microsoft 365, Azure AD to Entra, MCSE to role-based, on-prem to cloud to AI. But the through-line never moved: get identity right, govern your data, own your lifecycle, and the rest stands on top. Every era of the Microsoft stack rewarded the people who understood the fundamentals and punished the ones who only memorised the current interface. That's the bet I'd make again for the next decade. If you're navigating a Microsoft estate through this shift and want a second opinion on the foundations, get in touch.