Poll numbers show a staggering majority of voters oppose the Citizens United decision overturning limits on political expenditures by corporations. The numbers are high enough that a constitutional amendment overturning the decision isn't out of the question.
If there is a constitutional amendment, the next question is what the amendment should say. My home state senator, Tom Udall, has introduced what I would call a narrow amendment, which would enable Congress and the states to regulate corporate political expenditures.
A more intriguing option would be to draft a broader amendment limiting the freedom of speech to natural persons (i.e., not corporations or other artificial entities). This would have all sorts of effects outside of the campaign finance world. To name a few, this would greatly aid in the regulation of pornography and advertising.
About the only downside that I can think of (although I am sure there are others) is that a poorly worded amendment might enable interference with the press or with churches. Because the First Amendment separately protects the freedom of speech, the free exercise of religion, and the freedom of the press, however, I don't think it would be impossible to maintain those protections that I think most people would want to keep in the First Amendment.