Despite the popular use of the term President-elect, Trump is not the President-elect until after the Electoral College votes.  While it is a long-shot, there is still a chance that the voters choose to go differently than the electorate in their states.  Based on that, Trump shouldn't discard his business interests until after December 19th when he actually knows for certain he is the President-elect.  That leaves 19 days for Trump to say something so nutty that the electors cannot in good conscience vote for Trump for president.  That may raise the risk level for Trump.