Another alternative would be for each respective FA to withdraw from FIFA and form a new international body if everyone is upset with Blatter and the way he governs. Or to boycott the Qatar World Cup.
The problem with legal challenges when dealing with transnational organisations is deciding where such action should be taken. Different countries have different laws and local interpretation of those laws might prove extremely problematic. While I accept that each individual FA commits to some sort of binding contract, FIFA could feasibly turn around and say 'our competiton; our rules' and change any terms and conditions as they see fit. Plus, what would be the outcome of such a lawsuit? Renumeration? Reclocation? International arrest warrants for corrupt FIFA officials? The dismissal of Blatter? The dissolution of FIFA? What exactly would be achieved?
RE: football