As there are darn few (if any) engines that have worn out from normal wear and tear we don't have good data on how long it will last. If it hasn't had a new transmission put on recently there is a good chance that it could go at any time. If all of the wear items have been replaced these are the only two material items that could go wrong in the next few years.

Get an oil analysis and a compression check on the engine. If it is good condition and you've got an extra US3k set aside for a transmission rebuild then you should be fine. If the engine is iffy then set aside another US$4k.

I've got accurate repair data on quite a few high mileage vehicles. These are US domestics, Japanese, and MB. For all of these once you get past the warranty period if you set aside US$2k/year on average for a vehicle that is driven 12k miles a year or less you will have enough money to make the vehicle last forever and never get your hands dirty. This includes drivetrains, paint jobs, and interior rebuilds in addition to the standard maintenance. If you baby the vehicle and do repair work yourself you can cut that number down by at least 1/3.

If you have the reserve funds mentioned above and plan on keeping the vehicle a long time/forever the data indicates that on average you will be spending the same amount of money in the long run. So if that is your goal a perfectly maintained high mileage vehicle can be a good choice.