Light Novel Yahari Ore no Seishun Love Come wa Machigatteiru. (Oregairu) Volume 12 Spoilers Archive

A season 3 with one cour, or a movie are more than likely at this point in time, considering there's only two novels left after this one anyway.

The next two volumes need to have more than enough content to be adapted into a cour, or it would work fine just as a movie in any case.