The gun laws are missing from these graphs. How fast would America change its mind about them?
http://blogs.chicagotribune.com/news_columnists_ezorn/2011/0...
Long story short, acceptance of gun rights has been generally winning over gun control, though the patterns are almost the polar opposite of those reflected in the Bloomberg article.
Edit: It's worth pointing out that, true to form (for America at least), a lot of those states flipped colors as a result of a lawsuit, in which conformant legislation came after the fact.
Edit edit: I don't know how much editorial influence Michael Bloomberg has on Bloomberg News, but as Bloomberg News appears to be anti-gun, and Michael Bloomberg is quite obviously so, might there be a connection?