Death of the swing voter?

From The Week: "New research by Michigan State political scientist Corwin Smidt confirms that the percentage of voters who are truly 'independent,' swinging from party to party, has plunged from 15 percent in the 1960s to just 5 percent today. Crossing over party lines to vote for the other tribe's presidential candidate has become unimaginable. As Jonathan Chait put it … at 'New York': 'The dominant fact of American politics is that nobody is changing their mind about anything.'"