فَإِنْ قِيلَ: قَدْ وَرَدَ فِي الْحَدِيثِ نُزُولُ عِيسَى عَلَيْهِ السَّلَامُ بَعْدَهُ
One may object that traditions report Jesus descending after Muhammad ﷺ.
Jesus was already a prophet. His return at the end of time is not the appointment of another person to a new prophethood. His return therefore does not contradict the proposition that Muhammad ﷺ is the final prophet.
Two dates must be separated: when a prophet first received the prophetic office, and when a person who already holds that office returns. The latter is an event subsequent to the original appointment, not the establishment of a new prophetic office.