I would say that gaming laptops generally do not last longer than "average" laptops because they generally need to deal with a lot of heat coming from both CPU and GPU. Having said that it is very difficult to guess-timate how long it will last you before it fails (like from lots of heat). If you are going to spend that much money on a laptop and you want to use it for a long time, then you should consider buying an extended warranty.
My "gaming" laptop is a Lenovo IdeaPad Y470 and it is about 31 months old. I paid for a 2 year warranty and unfortunately, the nVidia GT 550m crapped out at around 27 or 28 months. I know it is the GT 550m that is the problem 'cause when I install the nVidia drivers (old, new, it doesn't matter) the Y470...