Well CO has sold its remaining in CM, at this time CM needs to decide what want to do if either follow CO or stay in the Skyteam. i personally think Copa would be in a better position with CO because both airlines have the same both FF and livery. we have to also remmember that CO is cutting some routes in LA and Copa can be useful to cover those routes with codeshare.
regards
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Forget the livery. There's no need to change it if they split, though they could if they want to.
The real cost for Copa leaving would be in starting up a new FF program or in switching to a different partner's program. Either of those would require a substantial infrastructure investment, which is why I don't think it will happen.