Billable Hours No More?
It seems more likely that the standard billing rate for these tasks will be decreased instead of ridding the entire system of billing hours. Some areas of law like divorce cases are not allowed to have outcome based compensation for attorneys.
The system I have set up for our clients is to calculate the amount of hours each task is worth in our local jurisdiction. As more firms use ai, the time for each task will decrease but will still allow the clients to work within the model rules by not charging an unreasonable rate for tasks.
Source: https://www.wsj.com/tech/ai/ai-goodbye-to-billable-hours-cba198fe