Old style CB ESA migration to new style

So we had the UC migration letter and begun the process. My husband has been on old style CB ESA since it transferred from income support. He received a letter today stating that he will now change to new style ESA and will need an appointment with a work coach and make a claimant commitment. Does this mean he will need assessing for CB ESA again? The IR part will be taken over by UC. We are lucky the DWP have not assessed him ever, he is still on DLA! So we shouldn’t complain, he is a lost cause. I just want to know what I need to be prepared for, in relation to gathering his medical notes etc…. He wants to stay on ESA and I know he needs to stay in the support group or it will end.