That is really a hard question to ask, kind of like asking how long will my old 460 engine last. Well it is a 1974 engine and it still runs strong. I even have a 1946 Dodge that still runs like a sewing machine. I had a honda that died around 80k miles once and my first land rover made it to 160k miles, the only reason it died was the frame rotted out. Engine still made power to have fun.
Has the oil been changed regularly, plugs wires, air filter. Has it been taken care of or is it a lease vehicle that someone drove and didn't care if anything was done. I even had a friend that had an old 3.9 Rover engine with over 500k miles but he was a maintenance freak his engine didn't even leak oil he took such good care of it.