I fail to see the logic in that. Ive argued the opposite of this for a while now. IMO, The fact it has blue ray and other great components should future proof the console over the 360. They have all the power and features to make good of the PS3. The only thing holding them back is software and machine price (Which a new console launch wont fix).
There's an opportunity, though, to fix a couple of architectural deficiencies the PS3 has that were forced by launch timing and pricing targets and still come out with a cheaper product in the end.
I could see a PS4 with:
2X the RAM
A higher-speed BR drive
Flash Memory replacing the Hard Drive (with HD add-on available)
More advanced Nvidia GPU
Even without significantly improving Cell (say just having a higher clockspeed), this would be a noticeable upgrade over the existing PS3 and could target a $299 launch price. Full BC with PS3 should also be easily achievable and sustainable.
It could be a smart move, actually, for Sony. It only sucks if you were a consumer who were counting on the "10 year" thing as a justification for purchasing a PS3.