The MFC Team grows MFC's feature set as time and resource allow.
MFC features are added when the MFC team feels that MFC can provide a clear win for C++ programmers over using some API or some system feature directly. MFC tracks features in the operating system as well as new strategic technologies that Microsoft introduces.
Unfortunately, some people in the industry have irresponsibly begun predicting what MFC will or won't support. If someone not on the MFC Team claims to know whether MFC will or wont support a particular feature, they're wrong: they don't know. If someone who _is_ on the MFC Team says that the team is planning support for a feature, they're probably right--at that particular moment in time. Because software development schedules change and are influenced by all sorts of surprises, the feature may or may not make the final version of the product despite the best efforts of the team members.