Seems current models will be replaced with ones that don't have disabled parts say the guys at Fudzilla & Expreview.

My bets:

GTS 550:
16ROPs/40TMUs/240CCs around 830MHz
192bit - 1.5GB GDDR5 around 3800MHz

GT 530:
8ROPs/16TMUs/96CCs around 780MHz
128bit - 1GB GDDR5 around 3400MHz