i'm sorry to tell you, but your PS2, is gonna die. Look what happened to Gamecube, and Original Xbox. They are gone because the developers wanted to make more money with better games with better features.
GTA IV could be on PS2, but they didn't want to waste their time doing it.
Once developers make a newer system they stick to it, leaving the old ones behind.
Your going to have to buy a 7th Generation console, or quit gaming. It's all your choice.
Plus, they probably couldn't fit the game on the normal disc, that's why it worked on blu-ray.