Although his remark was apparently in jest, Kerry of course has had presidential aspirations, winning the Democratic nomination in 2004 but ultimately losing to George W. Bush. At age 73 on inauguration day in 2017, Kerry would be the oldest president to assume his first term in the White House. (Reagan was older when reelected in 1984.) Kerry is about three years older than a more likely 2016 candidate present at Wednesday's ceremony, Hillary Clinton, but so far Clinton has declined to make known her aspirations.
Kerry had glowing words for Mrs. Clinton during his speech, saying, "Hillary Clinton came to the state department to rebuild alliances and restore our place in the world at a time when people were questioning it... and breathed new life into old partnerships..." Kerry's praise of Clinton seemed to come at the expense of her immediate predecessor Condoleezza Rice, George W. Bush's secretary of state during his second term, although Kerry did not mention Rice during his remarks.
A state department spokesperson said that a scheduling conflict prevented Rice from attending Wednesday's ceremony, and that George Shultz (who will turn 94 in December) had also been invited but did not attend, though no reason was given. The spokesperson also said that Kerry simply misspoke when referencing "six living former secretaries of state" when in fact there are seven.
Note: A version of this post first appeared at The Weekly Standard.