I think a really exciting thing they could do is RACIAL passives. Right now, race is pretty insignificant other than aesthetics because most racial skills stink and hardly anyone I know uses them. If they added passive effects, then it would actually mean something. And these could be done very balanced and lore-friendly.
For example, right now Norns have an elite skill for 4 primary spirit forms. I don’t know a single person who uses these instead of a class elite because they just aren’t good enough and have crazy long cooldowns. What if instead, you had 4 stances, each of the same spirits, that you could rotate between like ele’s attunements that would each grant a different effect, similar to the types of skills those elites already give you.
On the same note, Humans have elite God avatars. If they changed those to a passive that you could change when out of combat, maybe they could make some effect that’s not crazy by itself but could be a situational boost. This, or you could do something related to the charisma/personality lines that might grant unique effects.
In Sylvari character creation, you have to choose a day cycle that you were born during. What if you could alternate between those as well, granting varying effects?
In Charr creation, you choose an allegiance. If you could change that in and out of combat as well for a bonus, that would be pretty cool
The Asura might lend themselves toward brain power or invention related things. Haven’t really fleshed out anything, but hoping someone else who likes this idea comes up with something
What do you guys think?