The decision-making process of the future will be dominated by the organizations that provide the backbone of block generation. If they don't like a change in the code, they'll refuse to upgrade but will still keep 50%+ of the CPU power. A major dispute between bitcoin.org and the backbone would lead to a serious fork.
I very much doubt that any one entity will ever have 50% of the computational power. The botnet operators will bow to the whims of the community because it's the community that ultimately gives bitcoins value. What good is a giant load of bitcoins if you don't have anyone willing to give you something in exchange for them?