Microsoft's official Office blog is breaking the news that among many other accessibility-related enhancements to its Office products, Microsoft plans to improve support for PDF/UA, the accessibility standard for PDF documents and forms, in 2016.
End user software developers in the United States are aware of forthcoming regulations from the US Access Board and Department of Justice that will substantially affect large numbers of their end-users. It's likely, based on the US Access Board's draft of Section 508 distributed in early 2015, that PDF/UA will be among the standards adopted in some of these new regulations.
Microsoft's move towards PDF/UA is well-aligned with the forthcoming regulatory environment. If the company does indeed begin to support creation of PDF/UA documents from Office applications it will set a high standard for others in the office applications space, including Google, Apple, IBM, Adobe and many others, to follow.
See this useful and up-to-date (2016-02-23) summary of the legal and regulatory situation in the US.