With the PS2, many people would think that it would have died already. Let me be the one to say that that is not true. Even with over 150 million PS2's in the world, it is still selling. Reason? Well there is lots of reasons. One reason is the price. At $99 USD, it is a cheap console. It is not the current generation, but to some people it is because of the money. The games are cheap too. Some games are even 5 bucks. The PS2 sill has alot in it's life, even though the 10 year life cycle has more than passed.
Another reason? How about PS3 owners that don't own a PS2 but wants to get one. PS3 owners might love their PS3 so much that they might want to go back a generation and buy a PS2.
Sales figures are not known by me for now, so I can't post something like that. I'll update if I can. But do you like that the PS2 is still selling?