Writing a will isn't really "transactional", there is no negotiation involved. And wills are already a highly commoditised legal product. (So I agree with you that will drafting is ripe for disruption by LLMs, but don't think this indicates a broader disruption of transactional work or the profession generally.)

50 years is way too long a time horizon to predict much of anything

In 50 years time 95% of legal complaints will be decided by AI