PoliticalProf thinks the 10-year expiration date on the Bush tax cuts was always a mirage:
It was perfectly clear 10 years ago that it would be very contentious, politically, to let the Bush tax cuts “expire.” It was perfectly clear that, in 2011 (or 2010, as it happened), Republicans would scream that failure to extend the Bush tax cuts would mean imposing the giantest most horrificest and business crushingest tax increases on “the American people” in US history. In 2001, Republicans hoped they would be able to extend the tax cuts going forward after 10 years; Democrats hoped that they would have enough to votes to let the cuts expire. Both parties kicked the can down the road 10 years. The Republicans were on the winning side of that decision.