So, you have spoken.  I stand by 2015.  When they announce the release date at E3, you can say "I told you so".

Nintendo wants to hug you.

you mean when they don't announce the ps4 at E3? 

2013

PS4 dev kits have been sent out a little later than 720 dev kits but it isn't like they were going to make the games from scratch on PS4 right? ;)

The 1st few multiplats games that are in development currently on 720 can easily be ported to the PS4 by 2013 and I'm sure those few ports won't be like Bayonetta on 360 and PS3

I also NEED the PS4 to arrive in 2013 so I can pick 1 up in 2014(when it has a years worth of games in its library)

A while ago I would have said 2014, but now I really hope that it releases in 2013. Sales for the PS3 are down hard this year. They'll be down even harder next year, especially with the Wii U. It won't be sustainable if its the main console in 2014. Also, if the Nextbox gets the jump on the PS4, Sony would be giving Microsoft another headstart. This would dedicate a segment of consumers to Xbox Live, causing a domino effect where their opinions to spread to their friends. This would be irreversible and would hurt Sony in the long term.

What are the advantages to releasing in 2014? Releasing a more powerful console? That would be meaningless. When the difference in is the result of a mere year of technology, developers aren't going to bother maximizing the PS4. Would releasing in 2014 result in a strong lineup? Perhaps, but Sony could have a strong lineup if the PS4 released in 2013, so its not truly an 'advantage.' A year to improve power slightly simply isn't worth what they would be missing out on.

First, let's be realistic about something. Finishing in "first, second, or third place" is a fanboy metric. In business, you're not really judging your product from the release date of your competitor's product but from its own release date. You'll be looking at things like sales rate and market share first. You won't see a restaurant go "OMG that other restaurant opened before mine, they've already sold a million more hamburgers!" I know fansites will never get over this infatuation with "winning" a generation but for a serious discussion it needs to be put aside. When I opened my first business all I was really concerned about was if the market would bear another of the same type and how much share I could take.

Sony, provided they avoid the disaster of the PS3's launch, could release last and still do quite well. I think this generation has proven that. Even with all the hiccups, Playstation is still the second strongest brand globally. The PS3 is going to outsell the 360 by a comfortable margin this year, even with Microsoft releasing Halo 4 and a Forza title and the PS3 having no high-level exclusives, and next year will likely be more of the same. I think it's safe to say that fans of Sony games will wait for their console to launch, just like fans of Halo or Gears will wait.

Now, that being said, I think both Microsoft and Sony need to launch within 6 months of one another. This would allow them to advertise their own console release simultaneously with the launch of the competitor's console. If you're a fan of X brand and you know it's coming soon then you'll probably be able to hold off.

I predict the PS4 will launch in January of 2014. That gives them a shot at the Japanese New Year's money and Christmas money/gift cards in the west.

sales =/= profit

Goal of any business is to make profit. The only reason why they would launch a PS4 before late 2014 is out of fear of loosing a potential market to 720 or as you said the wii U in japan. Although, developer support for the wii U may just mean more developer support for the ps3, sony could go on the price offensive over there to compete with nintendo. I would personlly like to see them arrive late, lauch with a very powerfull system, a high premium price ($600- with the aim of making profit on every system not soon after launch) but the exclusives and application to back up the price. It won't sell the most systems, but financially it may make sense, although it may not please short sighted shareholders.

Well, they can't afford financially to launch one in late 2013 but they can't afford commercially to release it much later either. Releasing a console two or even three years after the competition can turn out to be catastrophic indeed.
Sony won't let MS get one year ahead and certainly not two years, and leaving Nintendo for up to three years is madness.

We've all seen the reports on their financial status and while it may appear that they are in dire straits regardless of what they do, they have also stated that they'll increase focus on the gaming division, phones and media.
They need a new and profitable console to compete with the next xbox and they probably need it in late 2013/early 2014 at the latest.

I think January still counts as holiday sales, especially in Japan.  Though I suppose they could pull a Nintendo and launch in the west first.