This is pretty much what I would expect, as I said here, and, before that, as Seth Masket said. I think there's a narrow logic, and a broader logic, and they are both correct. The narrow logic says that campaign finance laws are generally going to be at least one step behind the contributors; as Seth said:
But does anyone seriously believe that such laws have prevented Monsanto, Citigroup, or Exxon from getting money into the hands of political candidates? There have always been ways around these regulations. Corporate leaders can "encourage" their employees to donate to preferred candidates. And when wealthy people run up against an individual donation limit, they can always donate to a 527, a PAC, or some other independent organization set up by campaigns and parties. Beyond that, these laws have only been trivially enforced and the penalties for violating them are miniscule.And that's only campaign contributions. There is also lobbying money, and quasi-lobbying money, as seen in the Congressional Black Caucus story in the Sunday NYT.
The larger logic, however, says that of course large corporate interests are going to have influence in the American political system -- all large interests have, and should have, influence within the American political system. Of course the Senators from Arkansas are going to care about Walmart; that's what Senators do. It's not surprising, either, that large, easily visible interests are going to be, shall we say, well represented. That's going to happen regardless of campaign financing, regardless of lobbying, regardless of anything beyond being a large, visible, interest with clearly identifiable preferences. Of course, elections matter to all of that -- not every Senator from Arkansas is going to be equally overresponsive to Walmart -- but that's the nature of representation, just as representatives from some districts are going to be especially responsive to the concerns of Latinos and those from other districts are going to be especially responsive to the concerns of veterans. That's not to say that money never buys influence, but only that based on that larger logic it's not surprising that such direct lines tend to be very difficult to find, and probably matter only in particular circumstances (such as very low visibility issues in which a specific interest group is not opposed by another specific, narrow interest group).
Again, all of this is basically just the lay of the land when it comes to campaign finance. It helps, however, to know the lay of the land before trying to figure out how changes will affect the various players.