I honestly don't think that the Quartet's fukus (the ones we see in the manga, anyway) are their eternal ones. Sure, they have the bubble sleeves and the v-boots, but they also have elements of the basic fuku. What I think is that this form is their version of the basic fuku, and they'll get their own power-ups as time goes on.
In the case of Chibiusa, it honestly could go either way in my view. I personally could either take Chibs/Helios or leave it. I could, however, definitely see her being able to channel both the Golden and Silver Crystals. Maybe the two might even fuse when she becomes Queen and form something else (this could perhaps be the origin of the Lambda power that Sailor Cosmos mentioned)?