— It is a large assumption that it has been accepted as a change. Also most likely they already have their goals for the next few releases set. So pushing them to force it into the next update is very unrealistic.
A. Need agreement that it is a workable solution to be implemented
B. Has to fit into a release window that has room for the work required
C. Has to be accepted that this is something that they need to do in the first place.
Until the three of those happen, I would not demand they have it in the next release as it is really up to them on if, when and how it actually happens.
Not trying to be negative, it is just pretty rude to demand of them and assume they are doing what you have instructed. When they look at issues to fix they also have to look at the impact it has on their overall development cycle and any possible impact to the existing code. I would say highly unlikely waiting for the next release is going to help you unless they come back and say oh yes, that is our top priority to do currently.