Blago has probably been promised a pardon and minimal (if any) jail time in exchange for his silence.
I don’t think that’s going to work at this point... Blago was made to be the “fall guy”, and he’s NOT playing their game any longer. Plus, Obama is becoming too big of a liability for the DNC to sweep this under the rug. This may be their “OUT” (and SCOTUS and our Military’s way OUT as well) in regards to Obama’s eligibility. If he is impeached after being implicated in this, then the issue of his eligibility will simply fade away...