Yeah I don't see the problem here. C / C++ is pretty much platform agnostic these days and then just ifdef the platform specific stuff. Ignore vendor lockin crap like Java/C# and cross platform code is within everyone's grasp.
If you avoid crap like Python, you don't even need to frig about with bindings either.
Life is good if you cut out the bullsh*t and just use C or C++ :)
Edit: And if a locked down platform like Windows RT doesn't support standard C or C++... you jail break that broken crap until it does. :)