Despite receiving support from nearly all of its hardware partners, Microsoft's (MSFT -3.58%) Windows 8 has yet to catch on as a tablet operating system. Last July, Microsoft took a $900 million writedown on its Surface tablet. Though sales have improved, Windows tablets remain largely in the minority -- IDC's most recent data shows Microsoft's operating system with just 3.4% of the global tablet market.

But even that modest success could soon unravel. Both Apple (AAPL -2.88%) and Samsung (NASDAQOTH: SSNLF) appear poised to aggressively target the enterprise tablet market in 2014, perhaps the only market where Windows tablets have an advantage.

Samsung unveils the Galaxy Note Pro at CES
Samsung has been a longtime Microsoft partner, manufacturing and selling a number of Windows 8-powered tablets under the ATIV brand.Yet, its lineup of new devices could dampen demand for Windows tablets, particularly among business users.

At CES this week, Samsung unveiled its "Galaxy Pro" tablets -- a family of Android-powered tablets aimed at enterprise users. The flagship device sports a 12.2-inch screen, but Samsung is also selling Pro tablets in 8.4- and 10.1-inch variations. Regardless of the size, each Pro tablet comes loaded with a number of business-focused apps, as well as a special interface, and a number of productivity features (like the ability to have four app windows open at the same time).

Alongside its Pro tablets, Samsung has created a new business unit -- Samsung Enterprise Services -- a group centered around getting businesses to use Samsung-made mobile devices.

Will Apple roll out an iPad Pro for business users later this year?
Apple is expected to follow Samsung into the larger tablet arena later this year. For months now, various reports have suggested that Apple has a larger iPad in the works -- a variation of its popular tablet, likely to sport a 12- or 13-inch screen. Given Apple's propensity to use the "Pro" moniker with its Macs, Apple's new tablet could, like Samsung's, carry the Pro tag line.

It could also be intended for business use, at least according to analysts at Evercore Partners. They expect the device to ship late in 2014, and be aimed at the enterprise market. Many businesses already use the iPad in some capacity, and offering a larger, beefier version could reinvigorate iPad sales.

Will Windows tablets survive the onslaught?
If Evercore is right, Apple's new iPad could take a toll on Windows 8 tablet sales. Evercore believes Apple will pitch the tablet as sort of a middle ground between a tablet and traditional laptop -- a hybrid device in the mold of Microsoft's own Surface. Given the iPad's established mobile ecosystem, a hybrid device aimed at business users could be far more attractive than any competing device running Microsoft's operating system.

Still, there's one major factor working in Microsoft's favor: Its ownership of Office. Both Apple and Samsung's tablets will not be able to access the full version of Microsoft's dominant office software suite, at least not without streaming it from another PC. In the end, that could limit their adoption among business users.

Regardless, the trend toward larger, "Pro" tablets from both Apple and Samsung should be viewed as a major threat to Microsoft's Windows business, at least in terms of its success as a mobile operating system.