Sony built the PS3 with the intention of it lasting longer then the typical life cycle of the average console. Regardless of all the hacks that have been released I don't think Sony will be releasing a new console anytime soon.
Add-ons like the Move are intended to increase the life cycle of the PS3 and re-vamp consumer interests in the device.
Aside from devices like the Kinect and Move there really aren't any new leaps and bounds in technology applicable to consoles that would really benefit the creation of an entirely new next-gen console. Blu-ray is still blossoming and has a lot more time to really saturate the market. Sony can still ride the PS3 out for awhile with a few little revisions here and there like every console does.
If any console has a next leap to make it would be Microsoft with the addition of Blu-Ray or even an attempt at taking it to the obvious next level of digital media. I don't see that happening anytime soon either though. The Kinect has brought a nice boost to consumer interest in the Xbox and has in turn extended its life span. I'm not sure that the Move has done much of the same for the PS3 but it certainly buys them some time.
You also have to understand that the typical life span of consoles has increased with the ability of the manufacturers to apply firmware updates. You can't judge a consoles life span by the ones of the past like the delay between the PS1 > PS2 > PS3. Updates that used to require an entirely new console to be manufactured now just require a download or update on a game disc.
With all that being said, it's not to say that a new console with new technologies couldn't be produced soon, it just doesn't seem likely or worthwhile with what's currently available technology wise.