Yes that would be ideal - in practice it is also not extremely hard as most of these things aren't baked in to the compiler/linker but can be solved with (a lot

Yes that would be ideal - in practice it is also not extremely hard as most of these things aren't baked in to the compiler/linker but can be solved with (a lot) of #ifdefs. The harder part is likely getting such thing into the standard: decide what will be deprecated and what not.