I dont think they are expensive. I pay 150 eur/month for closing books and payroll with 3 employees. My accountant offered to do the bookkeeping as well for 250 extra. Its a pain to do but not 250 eur pain so I do it myself

Accountants could use AI themselves. Their customers will probably demand lower prices or just ditch them to automate it. It is a bit sad if AI disrupts this field, because it seems like a cooperative strength of humans to organize this synergy.

On the other hand I wonder if it will reveal the downsides of AI at a larger scale. Small businesses will have much lower tolerance for LLM inefficiencies. If it doesn't save time/pain it's just not worth it.