All may not be lost. As Rep. Barney Frank, D-Mass., said last night on the Rachel Maddow Show, [at approx. 8:00 min.] Congress has the constitutional power to regulate corporations as legal creations of the state. (Unlike people, corporations are not "natural-born" citizens, but must be chartered by a state of the union and are, thus, subject to regulation. This fact, obviously, was not pressing on the minds of Justices Scalia, Kennedy, Thomas, Roberts, and Alito when they arrived at their decision in this case.)
Although he wasn't specific last night as to possible remedies, I have a few of my own. One would be for Congress to pass a constitutional amendment kicking corporations out of the human race and send it on to the states for ratification. (Several NGOs are currently working on petitions to Congress to do just this.) Another would be for Congress to limit a corporation's expenditures in support of any one candidate in an election cycle to the same amount of money per employee that an individual could contribute to that or any other candidate. The last would be to pass an updated version of the Fairness Doctrine, stating that any media organization--print, TV, or radio--must devote the same amount of "air time" to each of the opposing candidates from the two major political parties, within reason. This would stop the fat cat corporations from buying up ALL the available advertising time during prime time, which they could easily do, otherwise.