Ok PS4 isn't going to be a PS2. First off the console market is becoming a lot more competitive than it was with PS2. There's less of a chance it will sell after the next generation is released. PS2 sold 50 million after PS3 was released, and I don't think PS4 will do that after PS5. Also, PS4 may have a shorter lifetime than PS2 and PS3. Maybe only 5 years to keep up with changing times. Not saying it won't win this generation just saying it's not going to sell 150m+
XBOX ONE/Wii U/3DS/PC
RIP Iwata 12/6/1959-7/11/2015
Thanks for all the great memories!