In commercial law, the business model is to rent the associates out to clients at rates higher than you pay (d/t your supervision). No client will pay $350/hour for your AI.
And for direct billing, it's not your interest to do things faster for the client (at risk of making a mistake).
So the real question is whether these pay-by-the-hour models will die as a result of competition from fixed-price transactions made viable via automation. I think not because the entire difficulty of legal work is that it's a complex bundle of issues until you sort them out; once sorted, there's really little to do other than execute (read: paralegals).