After a debug build with VS2015, my biggest concern is this:

  ..\PC\bdist_wininst\install.rc(19): fatal error RC1015: cannot open include file 'afxres.h'. [P:\ath\to\cpython\PCbuild\bdist_wininst.vcxproj]

There's also a slew of new warnings, mostly C4456 and C4457 with a few C4459s thrown in.  I think we can safely disable those three (which are all about name shadowing), perhaps with a XXX comment alongside to the effect of 'it might be nice to not disable these warnings someday'.

Interestingly, there's also this warning:

  C:\Program Files (x86)\Windows Kits\8.1\Include\um\shlobj.h(1054): warning C4091: 'typedef ': ignored on left of 'tagGPFIDL_FLAGS' when no variable is declared [P:\ath\to\cpython\PCbuild\pylauncher.vcxproj]

And a matching one for pywlauncher.vcxproj.