Some (but not all- for instance, cities in AK) of those cities will now have UX or QK service that CO will be able to codeshare on instead of AS. I would imagine UA and AC would of course prefer CO to ditch AS, and you'd get *A Silver/Gold benefits if you were on an all *A itinerary... so we will see what happens. (I think the status quo might linger for a while, at least until UA/AC/CO code shares become more popular.)