Off-the-shelf parts, no heavy R&D costs which hurt them with the Cell processor, and Blu-ray drives are much cheaper than they were when PS3 launched. Having said that, they COULD still sell at a loss, but I don't think it will be anywhere near as bad as it was with PS3. We'll have to wait and see.
Even still, They carry a .8133 debt ratio, meaning around 81 cents of the every dollar the company has in total assets would cover their debts. All of their divisions are bleeding money, their content divisions don't talk to their engineering divisions. The PS4, even with off the shelf parts, will cost probably ~600 USD for manufacturing per console, if they sell it for profit, they will get abysmal sales and uptake, no amount of hype can cover that. If they sell it for a loss, they will sell better, but not gangbusters, and will cause them even more losses.
Sony's debt is currently carries junk status, and they are a very bad bet on the market. They won't be able to continue if they don't pull a magic trick out. I'm not sure where they are going, but I doubt they will be able to continue in this race. Nintendo is always the company people like to label as "stuck in the past" and "doomed to failure" but Nintendo is still in great financial shape, their debt ratio is low, they have plenty of operating assets (money in the bank) and are able to focus on what is important to them, great games.
Sony is still carrying a mindset that worked in the 90s for them, when world economies were in great shape, people had plenty of disposable income, and could afford the commonly overpriced Sony products. Sony is basically Apple stretched too thin. When Apple moved into the mobile device business, it was a calculated risk, based on new technologies and high quality software that worked seamlessly with their other platforms. They haven't been moving into different industries since then, they have only been expanding their role within the mobile devices market. Sony has divisions that reach into both electronics and content, and none of it has been giving any solid returns for a very long time.