I know this is a little optimistic compared to the ending tone of the show but I think that the prophecy was at least 2/3 fulfilled. Four shall start/begin, true love will call, one shall betray and one shall fall.
True love will call = Brennan and Shalimar and/or Jesse and Lexa (maybe)
One shall betray = Lexa working for the Dominion etc.
One shall fall = Jesse's "extermination" date expiring (or if you want to go back more, Emma dying since there were four of them at that point too)