So no PS3 showing in 2012? That still leaves a 2013 release fully possible, albeit unlikely; there's still E3 2013, and we can probably (safely) assume that whatever year it releases in, it'll likely hit American shores in time for the Christmas season, as seems to be the norm for consoles... Though the PS2 appeared first in Japan during the spring, and both were announced/unveiled the year PRIOR to their release.
Since there's been no official announcement of the PS4 yet, a 2013 release seems less likely. If this claim holds up and E3 '12 passes by without a PS4 announcement, then odds are good it won't release until 2014. Of course, Sony could change this all by using a new release schedule, and simply showing a finished PS3 at E3 2013 and releasing later in the fall of the same year.
The older, latter model seemed to handle itself just fine after the younger sibling hit the market, and continues to see new games despite the PS3's growing momentum.
Sony claimed a 10-year lifespan for the PS1, even though the PS2 had squashed it out almost entirely by maybe 2003 or so. I think the PS2's longevity in spite of the PS3 is partly due to how big a drop in market share the PS3 has; from 150 million units and a 72.7% market share to 27.6% and 56; that's a drop down to nearly 1/3. In that case it only makes sense for developers who aren't so concerned about the "graphics" (as inferior to the PC as they are anyway) to simply make their game for the platform with nearly three times the installed base and market share. In the prior years, with the difference being even more severe, we saw this being even more prevalent.
The fact that apparently it's all too easy to just port a game from the PS2 to Wii shovel-ware style, (in spite of the Wii's greatly increased power over the PS2) makes it even more appealing from a market perspective: that gets you 44% of the 7th gen market as well, and a grand total of over 240 million units for an installed base.
This is also what's likely delayed the release of a successor. Sony's investors were almost certainly expecting that, given the 9-digit sales numbers and >70% market share scored by both the PS1 and PS2, that placing at least #1 was a foregone conclusion, even if it wouldn't be by such an embarassing margin. Given that, unlike the Wii's sales numbers, we're not seeing sales numbers decline from saturation, Sony can safely say that they have more market that will buy the PS3, so there's no need to waste R&D dollars and release the PS4 early when the PS3 is still competitive.
A similar story goes for the Xbox 360, at least with its current sales rates, so Microsoft, likewise, has less incentive for bothering to put out the next generation of consoles, and thus why we're seeing what we have now: over 5 years since the last (North American) 7th-gen launch, and only the Wii U has been announced.
The previous record gap between console generations (from the last NA launch of the older generation, to the first of the next) was 2 days shy of 4 years, between the Game Cube (November 18, 2001) to the Xbox 360. (November 16, 2005) Before that it was the 3 year, 8 month, 19 day gap between the Super NES (August 23, 1991) and Sega Saturn. (May 11, 1995) It's possible that the gaps are just getting bigger, (there was almost no distance between the 1st, 2nd, and 3rd generations) though the intervals had remained the same until now.