90k or so a year is not impressively high for a taxi, livery, or expeditor vehicle; that’s 246 miles a day; I’ve easily done double that on days where I am traveling in rural areas (like western PA) to explore and walk in malls (so not always driving). Last time I checked, for example, the engine warranty on a Mack truck is 5/500k, and truck drivers are limited to 8 hours out of 20.
The Metris is a stout vehicle structurally, the M274 is a stout basic engine (various issues not withstanding) and the 7G-tronic is said to be almost as stout as the electronic 4-speed known for million mile running between tear downs. I’ve seen lots of last generation Vito’s on European sites with double that mileage. I have no reason to believe you are looking at a vehicle that has reached the end of its logical life cycle- which is not to say repairs won’t continue to be expensive.