Is there a valid use case for replacing traditional deterministic automation with an agent?

I'd like to tap into the hive mind on this one. Is there a valid use case for replacing traditional deterministic automation with an agent?

When I think about this from a pure cost perspective, paying for agent tokens vs not paying for agent tokens is kind of at the heart of my question.

A few observations:

- Regular automation workflows are deterministic. AI agents are probabilistic.

- Agents do add utility and decision-making ability to automated workflows, which is a big plus when done correctly.

- Deterministic workflows can be triggered by agents, which removes the need for human operators - but in a practical sense, still requires human-in-the-loop.

- Deterministic workflows will probably remain the cheapest way to orchestrate automated tasks in the foreseeable future.

I can see a world where deterministic and probabilistic hybrid workflows come together in an orchestrated way. But is there a world in which deterministic automation is completely replaced by agents? Or just a use-case that is practical and is less than or equal to deterministic costs?

What I am trying to figure out is if there is a legit reason that an enterprise would replace stuff that works perfectly (and is cheap) with stuff that works most of the time and costs more.

Insight and thoughts are much appreciated.