re: #164 Mattand
I had read something last night that Trump is notoriously late for everything, and there was a real possibility that noon would come and go without the oath being administered, leaving Pence briefly as the acting president.
Apparently that spooked and upset him enough that he showed up on time.
I believe that would leave Nancy the Speaker as acting President. (Edited because I didn’t realize you were talking about 2017.)