In the windows 10 announcement they demoed a version of Office that supported the adaptive design. I don't know if they're dog fooding to get there though.
Beside that, MS Word, Excel, Powerpoint never used the native Win32 UI controls. The applications were developed in the early nineties with a custom UI library. Therefore it's highly unlikely that the full Office applications will ever be ported to another UI library. MS Word uses e.g. WinAPI "fibers" API, a rarely used WinAPI functionality that got popular again in recent years with Lua "goroutine" and Go "goroutine". The applications are based on OLE (Object Linking and Embedding) and MDI UI. The ribbon is implemented as an owner-drawn "menu" that overdraws the menubar. There are lite versions of Word, Excel, Powerpoint for WinCE that were ported to several different platforms including iPad touch version.
Beside that, MS Word, Excel, Powerpoint never used the native Win32 UI controls. The applications were developed in the early nineties with a custom UI library. Therefore it's highly unlikely that the full Office applications will ever be ported to another UI library. MS Word uses e.g. WinAPI "fibers" API, a rarely used WinAPI functionality that got popular again in recent years with Lua "goroutine" and Go "goroutine". The applications are based on OLE (Object Linking and Embedding) and MDI UI. The ribbon is implemented as an owner-drawn "menu" that overdraws the menubar. There are lite versions of Word, Excel, Powerpoint for WinCE that were ported to several different platforms including iPad touch version.
Office 95 italic "Microsoft" in window title: http://upload.wikimedia.org/wikipedia/en/f/f5/Microsof_Offic...
Word 6.0 in Win3.1, it looked like an alien on Win95 with "-" (Win3) instead of "x" (Win95) in popup-windows: http://www.windows-nation.de/Office/Word6c.png
Word 97 running on NT 3.5 (looks like an UI alien with Win95 look&feel on Win3.1 shell): http://upload.wikimedia.org/wikipedia/en/3/3c/Microsoft_Offi...
Office XP - looked out of place in WinXP which got a new theme at last minute; later the Win8 theme was inspired by OfficeXP: http://upload.wikimedia.org/wikipedia/en/a/ae/OfficeXP_Win8....