Star Alliance - Will waiting for CO to officially join give better fares on AC/CO combos?

I'm heading to GCM in January and have traditionally done it all on AC as a YVR-YYZ-GCM (and reverse) routing. Now that CO is joining *A, I was hoping that I'd be able to hop on CO for the return and do GCM-IAH-YVR since that shaves a couple of hours. Booked as one-ways that makes the ticket more expensive - does anybody know if waiting for CO's official entry to *A will make that routing cheaper when booked as one ticket?

I did send an email to AC and got a response that said "given that continental is joining on the 27th, they would imagine that you would be able to book code-shares on the 27th" which sounds something like "I don't know" to me.

Congratulations to your first post. I think the "I don't know" answer is as good as it gets at the moment. And even if they have joined it might take a while before all those fares are available.