My own view is that Blatter is secure as long as he stays in power because he has gone to great lengths to grease the palms of the various FA's and while he's in power he knows he can rely on their support. In return they get loads of money for their FA's.
Once he's out of power he's no longer relevant and all the skeletons will start to come out of the cupboard. He's a shrewd operator and knows this and this why he's clinging on to power for as long as he can.
My only hope is that the FBI investigation will lead to some of his lieutenants squealing in return for plea deals and that we hopefully see the extent of Blatters involvement.