I put it in quotations just because their isn't a defined class system, but different character builds suit different play styles!
Personally I think some sort of Spell Casting would create a really broad range of new "classes" you can play, such as a pure magic user, a spellsword or things of that nature! There's definitely the scope for it based on the existing game mechanics and presence of other magic users, but what would you guys like to see?
EDIT: I was in no way trying to suggest there actually be a class system in Valheim, "Class" was just being used as an umbrella term for different skills adding up to have a broader range of character builds. E.g. if you enjoy the archery and going out hunting/foraging and level up the skills relevant to these tasks then you're, in a way, playing a "ranger" style character. (There could be a new skill involving tracking like some people suggested that would also play into this "ranger" style character build)
Again, I'm not suggesting you pick a class on the character creation page and then you get JUST the related skills, that would seriously take away from the games scope for what characters can do.
Source: https://www.reddit.com/r/valheim/comments/wamni7/what_other_classes_would_you_want_to_see_in/