So I guess I need to determine whether or not the "PS4" will come out before I'm bored with FFXIV
Very little chance of a PS4 anytime soon.
There just isn't much room for improvement hardware wise, until duo-core or quad-core can be mass produced - and developers would need to write console software that can make use of multiple processors.
The blu-ray player in the PS3 is arguably the best blu-ray player available, due to the firmware upgrades that can be constantly updated via PSN. Other Blu-ray players just get left behind as the technology advances.
SNES - 1990
N64 - 1996
Gamecube - 2001
Wii - 2006
New Nintendo - 2011ish
Playstation - 1994
Playstation 2 - 2000
Playstation 3 - 2006
Playstation 4 - 2012ish
XBOX - 2001
XBOX 360 - 2005
New XBOX - 2010-2011?
Statistically speaking, if we follow the same progression (new console every 4-6 years), MS is just on the verge of upgrading and Sony and Nintendo should follow in a year or two.
But, as was pointed out, the hardware that would be required to mass produce a new console for any of the three manufacturers is not affordable enough to do so and still expect to make a tidy profit, especially when you consider that the current MS and Sony Consoles are both still at the $300 price range (360 is less if you get the cheaper arcade version) and companies usually don't produce their new console until the old one has dropped to $199.
On the other hand, Nintendo Wii is $199, but given that they are pushing the new Wii Black, I can't see them coming out with a new system until at least 2012.
So according to history, we should be seeing replacements in the next two years, but that will only happen if quad core or hexacore processors become way more affordable to put in a console.
Also, I gotta admit, we've come a long way from the days of Atari, Nintendo, SNES, Genesis, Playstation.... each console generation has had a noted improvement in graphics from the predecessor where you can stare at the current and previous models and the difference is quite apparent. The only video cards capable of meeting or beating out current gen console graphics cost $150-400. That's a pretty hefty price tag when you consider it has to be part of a console, -and- the developer has to make a profit.
Remember that the first wave of PS3s charged $500 for a 20 GB HD without wifi and $600 for a 60 GB with it. A Playstation 4, in order to outperform a Playstation 3, would have to cost -at least- $400 a piece to make, and that's being generous with the "Sony is buying a ******* of these parts" discounts. Given that most people who consider themselves to be primarily PS3 or 360 gamers are happy not only wiht their current gaming library, but also anticipating newer games, I can't see many people buying the new model yet.
Let's use SE as a benchmark for age:
FF1/2/3 = Famicom
FF4/5/6 = Super Famicom
FF7/8/9 = PS1
FF10 = PS2
FF11 = PS2/360 (PC is not a console)
FF12 = PS2
FF13 = 360/PS3
FF14 = PS3 (Could have also been 360, PC is still not a console)
So by the "three per system" rule, the 360 has theoretically (if we count 14, which COULD HAVE been on it if not for MS) had three games, the PS3 has had two. I can't say for sure, but depending on how much MS and SE have argued over the XBL Gold thing, FFXV may be a PS3 exclusive sometime in 2011-2012, leaving a theoretical FFXVI to be theoretically on a theoretical PS4 in 2013-2014ish (barring theoretical Mayan apocalypses).
So perhaps, realistically, we may expect to see a new XBOX in 2011-2013 and a new Playstation in 2012-2014. By then, we should have advanced our graphics and processors by 2-3 generations at least.