In general terms, I agree with everything you're saying. That's how it's always worked, but the point remains that people high up in the industry are looking for a change.
6 years would make it the exact same time difference as the PS2-PS3 period, which totally contradicts everything they've spoken about. Both MS and Sony execs agree on the subject, things need to slow down. There's always competition going on, which is what forces them to come out with new products in the first place, but when both companies agree it's not the way to go, but it's more than possible for them both to hold out. This is why both companies are constantly updating their current consoles and it's peripherals, they need to keep that new feeling for as long as possible.
As for this gen showing it's age, there still isn't much you can do that the general public will appreciate. You can improve performance but the jump from PS3 to PS4 wouldn't be much of a step when compared to the usual console upgrade and gamers would be more reluctant to make the switch as they were with DVD > Blu-ray. PCs will always be ahead of the game, but consoles are still far more popular, showing that we don't necessarily need to stay at exactly the same standards. Things are better than ever for the 360 and PS3 right now, with games like Call of Duty still raking in money and Kinect about to explode over Christmas.
If they do end up releasing new consoles in 2 years, they'll be doing it reluctantly.