I've stated this before as a possibility, but I think this kind of makes sense.
The PS3 is a 10-year console. That sucker won't drop to $300 until probably 4-5 years from now. However in 4-5 years from now, Microsoft and Nintendo will be bringing out their next systems. Even though the PS3 is selling around PS2 levels in Japan and GBA levels in America, do that for 4-5 years, and you can have a decent install base (~0.5-1.0 x GCN worldwide size). If the PS3 really is as "future-proof" and full of "potential" as Kutaragi and Stringer would have us believe, what's to stop it from "re-launching" itself again in 4-5 years with essentially the same hardware (maybe + Wii functionality)? That would be the same situation that Nintendo was in for the start of the GameCube, and they "re-launched" essentially the same system (2 x power of GCN) + Wii-mote and are doing gangbusters.
Maybe PS3 is just biding its time for the next round of systems, where it will already be entrenched with the hardcore and ready to pounce on the new HDTV-owning, "$300 isn't too bad" mass market that the Wii is now courting.
I guess it all depends on just how "future-proof" the system really is.
Edit:
On a side-note if Sony really did that, they'd just be re-proving Iwata's position of "diminishing returns." :lol