I feel your pain, but because Apple dropped model numbers in their naming convention and knowing their MacBook Policy, I purchased AC+ with future proofing my purchase in mind. Last year there was discussion of a 6 mo upgrade cycle but everyone thought Apple would be crazy to do so. I was surprised they upgraded so quickly this year, but it was not completely unexpected.
I am going to make a full faith attempt to get upgraded at no additional cost. I think others should do so as well provided you have AC+ or are within the original warranty period if you did not. Apple can afford the loss and should learn a lesson (not that they should not have expected people to demand this change).
Talk about entitlement!!!