Some ML applications will replicate expert behavior (e.g. document discovery in law) or improve on it (quant trading). A lot of the gains will be at the other end of the skill spectrum though.

Universal human abilities like speech and face recognition have made some low-skill jobs harder to automate than expert ones. We've only just invented algorithms that solve those problems adequately. If your vertical ML application is a machine that picks fruit when it's ripe, it's a stretch to call it an expert system.