Given all the talk of sedextuple cores and infinite ram in the PS4 hardware, it is my prediction that the PS4 will be an expensive console to make, but not as expensive as the PS3 was for its time. Reason being, goodbye to the cell, I hope I am correct.
Now, the PS Vita is a high-tech piece of portable console HW. It's my understanding that the PS4 will push graphics drastically, and that will also come at a price, a very Vita-ish price. Costly, sold at a loss, but not something that will require a second job (thank Kaz above). So, it's my understanding that the PS4 will be priced 400 to 500$ at launch.
Given that the successor to the xbox is the true jewel of the eyes of western developers of late, the exception are mostly 2nd party or closely tied to Sony, it's my understanding that most support will ignore the PS4 in waits for the successor to the xbox.
With all this said, I believe the PS4 will follow a similar HW sales trend to the PS3: very low at start, and a much slower time to arrive at peak. I believe it will cap at similar numbers due to what I understand to be their target audience.
However, the latest news on Sony's new marketting style could point to a more adequate tapping into the mainstream audience. If that is true I expect PS4 total sales to beat PS3 total sales closer to Wii lifetime numbers.
Thanks for watching.
