well considering they bought it at an extremely low point in bangkok's real estate market, and since then the market has risen by about 5.7%, they stand to make as much money when they sell as they would lose by renting the place for 3 years. that's an $80,000 swing.
Well of course if they can get it cheap and sell it for more you'll make profit.. don't forget the commissions you'll have to pay on it though.. let's say 3%.
Plus they'll have to bring the cash back to US right? So there's exchange rates to consider when transferring back... unless they hedged that, it's likely you'll lose some $ there too.