You are however entitled to represent yourself without passing the bar, and thus use the AI to help your case.
Even for the remaining lawyers, I imagine that their billable hours will crater due to competitive dynamics.
Billable hours will absolutely crater for lawyers who cater to a low-end clients (esp. for defense) and lawyers who are not good business people.
That said, the best lawyers will almost certainly still be in incredibly high demand, since higher-end lawyering (much like banking) is a personal business as much or more than it is a technical one. AI will simply allow these lawyers to do more and better work.