If that was the case then the PS brand would likely lose all respect it has. But that wouldn't happen, I mean come on $700 at launch?! haha the only reason it was so expensive for the PS3 was because Blu-Ray was a new technology and the Blu-Ray drive itself cost close to $800, the whole PS3 cost about $1000 to make so they were actually doing us a favor and selling at a near $400 loss.
And Sony is going to stick to Blu-Ray at least at the time being there doesn't seem to be any need for an upgrade. The Blu-Ray drive has decreased in price drastically since then and you can now buy a Blu-Ray player for $99 so I'm assuming the drive is around $70.
So what I'm saying is at most the PS4 will cost $399, And I expect Xbox 720 to go for the same, maybe Premium selling at $399 and Core $349. With the Wii 2 probably launching at $249. I wouldn't worry about inflation affecting us in the next year, maybe by next decade it will start to show, but its not a short term problem.