Why does the Torah add the words "Ad ha'Yom ha'Zeh"?
Ramban #1: Because Hashem had destroyed every last Egyptian horse, chariot and rider,
leaving Egypt a lowly nation, without horses, without chariots and without an army.
Ramban #2 (citing the Ibn Ezra): Because all those who chased after Yisrael were destroyed, together with their offspring in Egypt,
so that nothing remained of the entire family.
Seforno: Because all the Egyptian officers together with all the soldiers perished at the Yam-Suf, a blow from which they had not yet recovered forty years later, when they had still not been replaced.
Ramban: All of which were at the Yam-Suf .
Ramban: Otherwise, every person who dies dies forever and the Torah would not be telling us anything.
Ramban: 'Though this is not mentioned in the Torah'.