As I partially understand it, there are dual prophecies in Daniel 11:
1. In the first instance, "king of the South" refers to Judah and "king of the North" refers to "Israel/Ephraim"
2. In the 2nd instance, "king of the South" refers to Muhammed/Islam and "king of the North" refers to Europe (and possibly now also America, in alliance).
Part of the sealing could be the interchangeability of the terms. The 2nd instance, the battle between the "West" (i.e. "North" or eurocentric powers) and the "South" (i.e. islam) is still carrying on today. Some parts are complete e.g. crusades, fall of Constantinople.
In the 1st instance, some parts are complete: Queen Esther ("king's daughter of the south"), Judas Maccabbee (king of the south) etc- here the "North" varies from Greece to Rome, but I think possibly also at some stage to the lost tribes (Israel/Ephraim)
in Jesus' Name,