Law has one of the strongest "unions" in the form of the Bar Association, backed by legal force. You cannot practice law without "passing they bar" as they say. The lawyers who operate the Bar can just decide they wont be replaced and then they wont, AI will remain a tool used by human lawyers.
Easy, you can have a company scale a few lawyers into thousands of cases and call it a day.
The total number of working lawyers would dwindle if they are competing on price.
> 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.
Given they have the power of life and death in their hands having them licensed and accountable is peace of mind.
Surely unions are too powerful in several industries. Police, medicine, and law. But not having some association holding these people accountable is a bad idea.
Most of these industry guilds tend to be capricious but forgiving, determined to protect members. Almost every (North American) union puts its members' well-being ahead of any possible accountability, which makes sense, but means they cannot be trusted to self-regulate.