People might call the PS3 a failure for the following reasons: IF...
1. PS3 doesn't beat the Wii out in terms of sales. Hardware esp. or revenue.
2. PS3 doesn't sell LTD better than GameCube or even XBox.
3. PS3 doesn't make a profit (worse case) or the profit is marginal (say 2% on their investment)
4. Number 3 happens and somehow BluRay doesn't become the standard for HD.
5. Sony comes out with a new box 2 years from now, and discontinues the PS3.
My guess?
1 will happen but that doesn't make PS3 a failure. Just means it wasn't perceived as the best console by the buying public for the money.
2 would be a failure, I think all would agree, since it would imply 3. But 2 won't happen.
3 has the highest possibility I think. Though they did a great job of cutting cost so far.
4 looks very unlikely, and will probably be cited as PS3 best success story.
5 very unlikely as well.
Torturing the numbers. Hear them scream.