Windows 8 is Microsoft's biggest bet in 20 years - and three challenges could trip it up

The new operating system's success is no racing certainty...

...the end of 2012. Meanwhile, Apple and Google are not sitting still and the movement towards smartphones and tablets is accelerating.

Challenge 2. Windows Phone is disconnected from Windows 8

Although Microsoft has not gained significant market share with Windows Phone 7, it has generated a fairly robust set of applications. On the plus side, Windows 8 builds on the UI model introduced with the phone. On the down side, these applications must be modified to run on Windows 8.

While arguably any phone application should be modified to take advantage of the larger screen, the failure to exploit the Windows Phone 7 app environment to bootstrap Windows 8 Metro apps could limit developer interest in both Windows Phone 7 and Windows 8.

Challenge 3. Windows 8 targets the world

By trying to be all things to all people on all devices, Microsoft runs the risk of offering too little for anyone on any particular device. A Windows 8 tablet must be a great end-user tablet experience first. This requirement includes providing a core set of easy-to-use apps for functions such as email and calendar, rich browsing and media consumption.

It also means having a robust ecosystem of third-party apps optimised for the tablet. A common platform across desktop and tablets and support for Windows 7 desktop apps are nice but will not matter if the core tablet experience is inferior.

The next 12 months will be an interesting time both for users and developers as the shift away from the UI model we have known for the past 20 years continues. For Microsoft, it's all riding on Windows 8. Will it be OS/2 or will it succeed as Windows 3.1 did? Only time will tell.

David Cearley is a vice president and fellow at analyst firm Gartner.