Technically cantrips are still arcane spells, as are rituals, so if the rule remained as is now, from a FAQ article I would expect that the official ruling would be that you still cannot cast them in armor. This would also be consistent with 30+ years of previous editions.
But... considering the following:
- for a single-class Wizard it makes no difference: she is not going to wear armor anyway because armor prevents her from casting her regular daily spells
- cantrips are already "officially" easier to cast than regular arcane spells because they don't need to be recorded in a spellbook; fluff text already talks about the caster knowing them very well
- the cantrips granted by races or feats don't make much difference on a Wizard of such race or specialty, but they make a nice difference to a non-Wizard... not being castable in armor kind of defies the whole point of taking the feat or granting the racial benefit (maybe not the whole point, since you could pick non-combat cantrips and still find them useful during downtime, but let's say not being able to use them while in action would make the feat severely less attractive)
- rituals always require enough time so that they cannot be cast in the middle of action; if you disallow rituals in armor what do you achieve? That the caster always takes off the armor, cast the ritual, and puts the armor back on... 99% of the times if she has time to cast the rituals she also has a few extra minutes to remove the armor and put it back
Because of the above, I think it's much more reasonable to allow both cantrips and rituals in armor, including those granted by the Wizard class itself.
I'd like to see bigger buckets for spells. If you're a wizard/sorcerer, and you learned burning hands as a 1st-level wizard, you just know burning hands. You can prepare it in your spell slots, or you can cast it with your willpower points. You wouldn't have to worry about which spells are from which sources; you just have a list of spells that you know. (Maybe separate buckets for arcane and divine, but that's it.)
Then you can have a general ASF rule, and anyone who has a level of dragon sorcerer can be immune to ASF.
In this case, I'm not with you. The explanation on the source of magic for those two classes is already strongly defined and strongly different, and I don't think it should be automatic to shift spells from one to the other "daily pool". Perhaps I might accept it with cantrips, but it's a moot point because cantrips are already at-will anyway.