I'd say sometime 2013 just for the announcement to be honest. This generation is just now beginning to peak, so they aren't going to pull out anytime soon. Companies are JUST NOW learning to embrace the technology of the PS3 as far as development goes and with new peripherals being released there will be more room for growth. 

Nintendo will start rapidly losing market share to the PS3/360 throughout 2011 and will start development on their next-gen console rather soon. MS/Sony will hang in there for roughly ~3 more years. They may both begin various development processes as far as deciding what type of hardware they want to use and at least set goals as to an architecture outline. MS will start to search for other forms of disk media to write games on, and Sony will probably either continue to use Blu-ray or release a BR2 (different name, obviously) that basically uses the same format as BR so it can be read by current players, but has a higher capacity.

I personally think both of the next-gen consoles from Sony/Nintendo will start to further ascend into the realm of PC hardware formats, kind of like they've done this gen utilizing standard 2.5" HDD (yes MS does it too, and installing a 2.5" HDD isn't much harder than doing it in a PS3), USB 2.0, and a more advanced operating system.

All-in-all, this generation is far from over for MS/Sony. Nintendo will jump the gun on development as their market share starts to rapidly deplete with the Wii. MS/Sony are just beginning to peak (2009/10/11 are all going to be GREAT years for them) and will ride out the current gen until they've at least hit ~30% market share each.

Nop, PS4 will be released much later. 2016 or so, the PS3 sales haven't exploded yet.

I don't think sony will launch a new console in 4 years from now.

when the ps3 launched, Sony thought that all the developers would use everything the console had in it. but it took 3 years for them to finally take a lot out of the ps3.

even so, multiplat developers (due the xbox360) barley use 30% of the ps3. so I think the ps3 has a long life to go.

all i'm saying is this,...i'm not buying into the next gen right away like i did this gen.  i've got a lot of wasted money on consoles i don't use this gen so i'm waiting at least a year into the next gen before i decide which one i'm getting.

Late 2012 has been my guess for both X720 and PS4 for some time now. Wii-2 should release next year.

U think its possible PS4 might come in 2012? That's just two years from now. The PS3 just started to sell to the mass market. I think PS3 needs another three years before it can be disturbed with a new Playstation.

I reckon the ps4 will release in 2016-2018. I think the xbox720 will release in 2012 ansd the super wii but instead of releasing a new console sony will compete with the ps3. i.e reversing the situation this gen, where sony have the less powerful, easier to develop console with a masiive install base. That way sony could buy lots of third party exclusives and finish off microsofts next bot even before the ps4 releases.

Do you seriously think that Sony is going to let both Nintendo and Microsoft release their next consoles and let them go uncontested for 4-6 years?

Xmas 2012 or Xmas 2013. If they're aiming for 2012 then they must have next-gen games in development already.

I think once the new Xbox console is released the 360 will go down to one SKU. The 250 GB or an even bigger HDD for $149. The 360 250 GB and PS3 will both drop to $199 Holiday 2011.