These cars are now favorites for urban taxi use. Talk to some taxi drivers!! The Prius is head and shoulders above any other hybrid car on the market, so expect it to have typical Toyota life expectancy which I have witnessed can be up to a million miles under the right circumstances.
Budget for a new battery every 10 years at $3000 or so.
As others say, just keep driving it and do the prescribed maintenance and you may be surprised how long that car will give reliable service.