Not afraid of it, but it’s worth mentioning that Trump, Sanders and Clinton would all easily be the oldest first-term president ever elected.
Actually, in one of the posts Professor Kalt notes that Trump and Sanders will be a little older on Election Day than Reagan was on Election Day 1980, while Hillary would be less than a year younger than Reagan was. So, yes, one of them could die between the date on which the Electoral College meets and the day on which Congress would count the electoral votes (and, if no one had a majority, that the House would elect the president and the Senate the VP).
Frankly, while I support the adoption of legislation under Section 4 of the 20th Amendment to deal with the possibility of such an untimely death, I think that an easier, and more important, congressional statute would move the date on which the Electoral College meets in each state from its current (federally imposed) date in early December to January 2, the day before the new congressional term commences. That way, if a presidential or VP candidate dies between Election Day and January 2, the presidential electors can vote for a replacement prior to the electoral votes being delivered to Congress. This would largely eliminate the risk of a dead person being one of the candidates to be considered by the House for the presidency (or by the Senate for the vice presidency). Perhaps even more importantly, such change in meeting date largely would eliminate the possibility that the outright winner of the presidential election is a dead man, which either would result in the VP-elect becoming president on January 20 or, if Congress followed its (stupid) 1872 precedent that electoral votes cast for a dead person (in that case, Horace Greeley) would not be counted, perhaps permitting the House to elect the loser as the new president.