Proof to what? The RAM increase in the PSP was about battery life more than anything else. In the PS3 since you aren't worried about reducing optical reads to save electricity then all doubling the XDR does is increase the build cost.
How about Slim PSP and old PSP cost in production now?
PS3 Line product along in 10 years life cycle, maybe 2010 or 2011 is the time for new PS3
revision. Let see to proof.