The five-year long march to developing Windows Vista exposed just how broken Microsoft’s Windows-development process is. It took far too long, major features were dropped along the way, and it was wrapped up in more red tape than the IRS. That’s why I think that Vista will be the last of the “big-bang” Windows releases.

Mary Jo Foley has an excellent analysis of what went wrong during the Vista development cycle. As one example, she cites the fact that it took more than 40 programmers a year to deliver the the final Vista Off button.

Overall, the problems are obvious: bloated staffing, too many levels of management, and far too much bureaucracy. Microsoft has become the slow-moving, bloated company it vowed it would never be.

Everyone I’ve talked with at Microsoft recognizes the problem, and I think they’ll take care of it. The next version of Windows, the company claims, will take closer to three years than five, and will be a far more incremental upgrade than Vista was. In fact, it sounds as if Microsoft has all but given up on its attempt to remake the underlying file system into a true database.

The next version of Windows will feature incremental changes rather than dramatic ones. But I’m not entirely sure that after that, there will even be Windows upgrades in the sense that we now know them. Rather than upgrade the entire operating system, I expect Microsoft to instead offer online-upgradable modules and feature sets. In this model, you wouldn’t ever buy an entirely new version of Windows (except on a new PC, of course). Instead, you’d buy a subscription to Windows, and pick and choose which new features to install.

This would not only allow Microsoft to simplify development, but it would give the company a steadier revenue stream, via subscriptions rather than operating system upgrades. The change is inevitable. We won’t see any more massive Windows upgrades as we’ve seen with Vista.