You had better believe the Obama administration has already given this a lot of thought.
During the primary season leading up to the 2008 elections, the Democratic National Committee floated an idea to take control of all 401k accounts in the country as a way to "save Social Security." Although that idea was withdrawn after causing much controversy, it has been leaked out several times since then.
Watch for bank assets to be taxed as soon as they can figure out a way to keep everyone from making a run on the banks. Since we have what's called a fractional reserve, banks only keep about 10% of total deposits on hand. The rest of the money is just numbers on a computer print out. A bank run would cause major catastrophy.
In Cyprus the banks were all closed before the announcement, and remain closed still.