A new OC is NO Panacea.
Even if we get a new OC, it won't do any good for this year. What is a new OC going to do? He or She will have a whole new scheme and playbook. You are not going to introduce a new scheme mid season. Maybe add a new wrinkle here and there. That's it for 2018. Also, a new OC won't know jack about the current plays or the or players capable of executing the existing offense let alone something new.
Unless Richt will demand that the new OC learn and use the existing playbook. You will have the entire QB room and offense learning a new scheme and playbook. Therefore, you can write off the 2019 season because it will take a full season to execute a new scheme and plays including offensive line blocking schemes at a high level.