As Microsoft has seen with Windows XP, it's not just users' operating system dependencies that can keep them from upgrading; it's their browser dependencies, too.
The same way that IE6 was the browser that Microsoft built into Windows XP -- and around which many business customers standardized -- IE8 is the browser variant that Microsoft integrated into Windows 7, which is the newer version of Windows favored by many business users. Similar to the case with Windows XP, many businesses have built and certified line-of-business apps specifically for the Windows 7/IE8 combination.
Here's the catch: Even though Microsoft treats IE as part of Windows, it's also still an independent piece of software. Microsoft has rolled out subsequent IE releases (IE9, 10 and most recently, 11) that can run on Windows 7. But not every enterprise is willing or able to move to these newer IE variants, in part because their companies have standardized on Windows 7/IE8.
This situation becomes especially problematic for Microsoft and its customers as Microsoft rolls out new software and services that no longer support the older IE variants. For example, Office 2013 and Office 365 don't support IE8. If a company is stuck on IE8, its admins might understandbly be reticent to move to Office 365 if IE8 isn't supported.
There may be a Microsoft-made solution to this dilemma, however. Sources say it's a new IE feature known as EMIE.
Enterprise Mode for IE (EMIE), as it's referred to internally, is supposedly going to be a new feature of IE11. According to my sources, EMIE will allow businesses to specify which sites should be loaded in IE8 compatibility mode and which don't need it. Users who need IE8 to view certain intranet sites and internal apps would still be able to move to(or Windows 8.x) thanks to the new compatibility mode functionality. But they still would be able to make use of all the rest of IE11's features the rest of their browser needs.
I've asked Microsoft whether the plan is to include EMIE support in Windows 8.1 Update 1, or if this capability will be rolled out separately at some other date. No word back so far from the Softies.
Update: The IE team had no comment on this post, according to a spokesperson.
Update No. 2: @AngelWZR is confirming that "Enterprise Mode" is built into the leaked Windows 8.1 Update 1 build from January 17. It is part of the built-in IE 11.0.3, he says.
"Enterprise Mode helps improve the compatibility of websites identified by your company," according to information in the Windows 8.1 Update 1 files, he says. But the feature is currently locked, he reports.
Update No. 3 (February 3): @WithinRafael also confirms the Enterprise Mode feature and finds it to be unlocked in a leaked build of Windows 8.1 Update 1.