Sony's only mistake was making the console with blu-ray. Sorry to disappoint you all, but the cost would have been at least $200 dollars cheaper at launch and most likely $300 or $400 less. And I understand Games like MGS4 would have been harder to make, but 90% of the games don't use all of the blu-ray space in the first place. And if you think about it, it's not Sony's job to make a console with more disc space. Just one that can sell.
So since the PS3 was $500-$600 at launch in America, They have sold 16 million unit's. Now think about this, If the PS3 used a DVD played instead, that lowered the price to $200-$300. The price of the others at launch only with a twist. You have a choice to get the worse console for $100 Dollars less. I don't think the price drop would have come yet, however a 80GB PS3 has more power then a 360 arcade. So the PS3 would have most likely sold over 50 million units! And they would be making money on their consoles.
Is Blu-ray the reason Sony is failing? It seems quite possible. I see Blu-ray as a leech which should have never been attached to the PlayStation's success. And don't get me wrong, I love blu-ray, but Sony's job is to move consoles.
They could have done so many things better. Even if they used a HD-DVD player as their main player they would have done better then blu-ray.
As for the PS4, Don't expect much. I assume they will make a PS3 and a half like Microsoft did with the xbox.