İf you practice an open book exam you will have to ask much harder questions, and the actual becomes fishing for chatgpt's mistakes. This lacks repeatability because you don't know if and how it's going to hallucinate on any given day. And the level of questions you'd need to ask would be beyond many candidates. İn a closed book setting I can ask to implement a basic dynamic data structure and get all the signal I need.
I think the signal there is going to be how developers perform with assistance. The goal of the software is to solve the problem, after all. If they do it faster and better than everyone not using it, well, I guess we’ve figured out who to hire.