George Lucas was likely motivated by the looming 2013 tax increases when he chose to sell LucasFilm in 2012, according to this Wall Street Journal Article.
As I previously posted here, there are unprecedented estate tax and capital gains tax savings opportunities that are set to expire as part of the "fiscal cliff" at the end of 2012. Capital gains tax rates are increasing, estate tax rates are increasing and estate tax exemptions are decreasing. Plus, the Affordable Care Act (aka "Obamacare") added a 3.8% surtax on investment income for those earning more than $250,000.
In the end, Lucas likely avoided an 8.8% capital gains tax increase. The estate tax and gift tax exemption is also five times larger today than it will be in two months. All in all, selling now was a win for Lucas.
Of course, you don't have to be a multi-billionaire movie maker to take advantage of this. Planning now is a good idea for any business owner or investor with total assets (business included) in excess of $3-5 million.