One of the concerning things to me is the possibility of a repeat of 2000. Trump/Clinton has changed some of the normal election dynamics and my hunch is that the changes increase the likelihood of one candidate winning national popular vote, and the other candidate winning the electoral college. (My idea being that Trump may suppress margins in the red states but do well enough in blue and purple to squeak through.) If that happens, the lawyers will find a way to litigate.
Jonathan Adler at Volokh speculates that Justice Ginsburg has now take steps to ensure there won't be a 4-4 split in the Supreme Court on any election issue.