Octave already treats whatever follows % as a comment, so nothing
prevents you from writing end%if or end%for already. Doing so makes for
code that is both Octave and Matlab compatible.
it's compatible, but as mentioned earlier using end instead of endif loses Octave's 'advanced diagnostic abilities'. end%if is still just end as far as Octave is concerned. I can't imagine, though, the level of interpreter changes that would be required to have it selectively parse something that would otherwise be handled as a comment, and the number of false parses this could generate.