Zones on 08 December 2008
The real answer is, because PS3 is way over it's time, the system is more future proof than the other ones. Now, just because it didn't sell as much as PS2 doesn't mean the system can't be out for as long if Sony supports the system.
Another thing that you should know, is that PS3 is in it's infancy as of now, outside few first party studios games, no company took advantages of the system, we really don't know what it's capable of until now. But I am sure whatever you saw on 2005 E3 press conference is completely possible on PS3, so two years form now, the system, might be something you have never thought of.
