But that's still no reason to drop multi-out. Many people still will not have HDMI equipped TV's by the time the PS4 comes out. For the pennies it would cost Sony to include multi-out they'll be able to shift more consoles on top of that simple inclusion.
You throw "...many people..." & "...pennies..." out there and I don't necessarily agree with either.
According to In-Stat, roughly 90% of the Televisions manufactured in 2007 had an HDMI port. I can't find a statistic for 2008-9 but I would guess it's even higher. The fact is, if you purchased a TV in the last 4-5 years it's VERY likely that it has at least one HDMI port. If you purchase a TV today or tomorrow or in a year from now or probably in even in
2 years from now, I would guess it's better than 99% that it has multiple HDMI ports. At which point in time, the PS4 probably will not yet even be on store shelves. We're taking a long look into the future here.
(Long of course being relative)
So if > 75% of the people in the market for a PS4 (at the time of it's release) have an HDMI enabled TV, I'm guessing this will be the de facto standard. And what about the other 25%? It's important to understand, part of the reason Sony wants to sell you a PS4 is so that you go out and BUY the latest and greatest TV (and hopefully from Sony). And naturally this goes hand in hand with Sony selling the latest and greatest 3D TVs, hoping that you'll go out and BUY a new PS3 or 3D enabled blu-ray player (or eventually PS4). Sony doesn't want to be your friend. They just want your money.
The PS3 lost some hardware features along it's life through various revisions (2 USB ports, card reader, etc). There may have been other political and marketing reasons for this. But I'm sure the main reason was to reduce the manufacturing cost. How much I can't say but I'm sure it was more than a few pennies. Eliminating the multiport would probably save as much as a few dollars on every PS3. It's not just the cost to manufacture and buy the hardware but one has to consider the additional R&D & QA that goes along with it. Over the course of the PS4's life and depending on how many sold, it could potentially save Sony hundreds of millions of dollars. And you can bet your life, that they'll also attempt research and gauge how many new TVs they'll sell due to the elimination of the multiport vs any lost potential console sales.
Difficult to judge, the future is.

But certainly, Sony is still smarting from their mistakes on the PS3. It was perhaps a little too advanced (meaning expensive) for it's own good when it was released. And Sony themselves would probably argue that they may have pushed that envelope a little too far back in 2006 at at time when most people probably weren't ready to take advantage of it. And I'm sure they'll be mindful of this with the PS4. Indeed, combined with the severe economic slowdown, none of the big 3 seem eager to unload a new console design with new standards on us
anytime soon. But when they do, the majority of living rooms will look a bit differently than they did in 2006.