Sony might be selling the PS4 at a slight loss, but the company expects that shortfall to be covered by most customers' initial purchases - specifically a PlayStation Plus subscription and a launch title.
Speaking to Eurogamer, Sony Japan executive Masayasu Ito skirted around specifics on the cost to Sony of each PS4, but was unruffled by the negative margin, saying that an "average" customer's inital investment would cover the gap. He wouldn't elaborate on what that margin is, exactly, but analysis estimates it to be somewhere in the $60 range.
Sony has already said that it expects the PS4 to sell more quickly than the PS3, and that the business will recoup its launch losses on the machine much earlier in its life-cycle. With off the shelf components getting cheaper much more quickly than proprietary hardware like the Cell processor, the PS4 should also find itself turning unit profit on its own before too long.
Microsoft, on the other hand, is selling the Xbox One at break-even or profit from the get-go, resulting in a higher street price but a clear increase in business stability.