Then most likely we would have a government openly controlled and run by corporations and other enterprises, for the benefit of the few. This has been illustrated most clearly in Space Merchants written by Frederik Pohl and C. M. Kornbluth back in 1958.
The world in which the story takes place is one that we can be scared of as easily (maybe even easier), than they were back in the late fifties when the book was first published. Big companies have taken over the American government, so much o that Congress is no longer composed of state elected officials, but instead it's comprised of the representative of big companies, such as DOW, General Motors and General Electric; the president of the United States is a figurehead, with no real authority whatsoever, advertising companies rule the industry and social classes are determined by your profession.
So far this world is not something we have not feared (with the exception of advertising not being as powerful now as it once was), but the real cherry on the cake is the dreadful environmental devastation brought about by the total lack of government control over industry and their ever greater need for more resources.
Another example is found in Kim Stanley Robinson's Mars Trilogy. In this story the plot is so much bigger than in Space Merchants that the issue of corporate control of government is not as big (in terms of pages devoted to it), but it is pivotal to the development of the first colony on the red planet; in this not so future Earth multinational companies have become something bigger and scarier, they have become Supra-National Corporations, they are above governments, they can basically do whatever they please, and that has led to overpopulation, toxic waste poisoning, famine, and countless other misfortunes that are the trigger for the expedition to Mars; an expedition from which, win or loose, the people involved will never return.
The truly frightening and at the same time astonishing thing is that all the stories I have come across that deal with a scenario in which government is controlled by corporations, paint this as a catastrophic event, as one of the worst thing that could happen to our democratic societies.
Do you think that of government falls under the open control of economic powers the world will be such a nightmare? or is it possible to find a positive side to economic control over government?