I imagine they will need to keep the COs on whilst they are in the throes of merging and downsizing since the CO is involved in the recommendation and co-ordinating of the merger and he is essentially the link betwen the congreagtions and the branch.
It also makes sense that as congregation mergers continue resulting in fewer congregations, talks become videos and more things are done online they will need less COs. Since the CO arrangement is an expensive one I can see them finding an alternative in the future.