The Devolution mod itself still operates. Other mods don't. (Or at least aren't supposed to: have had a few instances where some stay active despite it being dead...)
The rank of the Devolution mod only change things like Panzer's quill damage, Crescent's charge damage, and Sly's evasion chance / duration. Nothing huge, so you can likely keep it unranked (for mod capacity) or rank it up and see little major difference.