Here's how I predict things will go for the newest Pokemon currently without an evolution line:
>Wooloo: One Evolution After First Form
-Corviknight: No Evolution or Pre-Evolution
>Drednaw: Pre-Evolution Possible, But Unlikely
-Yamper: No Evolution
-Alcremie: No Evolution
>Rolycoly: Two Evolutions After First Form
>Duraludon: Two Pre-Evolutions Before Third Form
-Morpeko: No Evolution
-Cramorant: No Evolution
>Polteageist: One Evolution After First Form
>Impadimp: One Evolution After First Form

My concern is that Dynamaxing/Gigantimaxing might result in many Pokemon who COULD have an evolution line not having one due to the gimmick being prioritized.