Do you think this attraction came to be solely because of the approaching "public domain" licensing? And Disney creating the ride for further justification in keeping Mickey within the company?
I can't see how this would be related. The copyright expiration is coming up on a few of the original shorts, but Disney still holds the trademark on Mickey. If anyone is truly going to try to make a case that Disney isn't invested in Mickey so should loose the copyright, a new ride is hardly going to make a difference.