Besides the house rule option, I would think that a theme is primarily a bundle of mechanical benefits based on a story element. I don't think a theme is meant to be treated as a prerequisite for a story element.This is, at the same time, interesting and worrying. It's cool because looks like I will be able to create aasimars, durzagons, etc. with just human race and themes.
On the other side, if I can only choose one theme, I won't be able to make an aasimar noble, because I must choose between either one, as both are themes.
IIRC it will be Race, Class and Theme.So basically, it sounds like pick a starter option (class). Then pick templates to add on top (race, theme, whatever).
I like it. (not much different than before).
Besides the house rule option, I would think that a theme is primarily a bundle of mechanical benefits based on a story element. I don't think a theme is meant to be treated as a prerequisite for a story element.
So I would think that you could be a noble aasimar, while taking just the aasimar theme. But you wouldn't get any mechanical benefits from being a noble. That would merely be part of your story