When I said that it makes sense, I meant that it makes sense when you consider the normal cycle of console releases. I didn't necessarily mean that it makes sense from a business standpoint. That being said, I think a 2012/2013 release would be fine.
Sure, they're probably either going to lose money or have a very small profit margin to start with. Though I don't think Sony will have the same kind of issues in this area that they did with the PS3. Now that Bluray has been established, they don't have to eat the cost of supporting an expensive new medium. The cost of putting a Bluray drive in a console in 2012 will be nothing compared to what it was back in 2006.
Aside from that, the new console will probably just see the typical type of hardware upgrades. Much more RAM, processing power, storage capacity, etc. These are all technologies that jump leaps and bounds over the course of 6 or 7 years.
Plus, it's not like they're going to take the PS3 out back and shoot it when the new console drops. Just look at all the of the success that the PS2 had after the PS3 was released. As long as they support it like they did with the PS2, the PS3 will be seeing quality titles at least a few years into the next gen™.
Most of us don't even think about a new console purchase until it has been out for a couple of years anyway. The hardcore guys will be there in droves to support it on day 1 and throughout the first year or so, but most of us will still be happy with our "old gen" consoles for a little while longer. Which is great, because by the time I buy a PS4 in say... 2014/15, the price will be down and they will have had a couple of years to work some of the kinks out.
I dunno, maybe I'm one of the only guys who feels this way, but I really don't see a problem with things playing out that way. At that point I will have owned my PS3 for 6 or 7 years, and will be excited to look into buying a new console that isn't running off technology that will almost be a decade old at that point.