The cabal emperor, savathun, xivu arath, quria of the vex, house of kings kell, possibly uldren or Mara sov. If they take the game in the direction that I am thinking and we end up freed from the traveller and the traveller starts taking over guardian's free will, then we could end up fighting ikora Rey, zavala, cayde 6, and the speaker. We could fight the nine, and that could really be anybody since we know basically nothing about them. We could also fight Rasputin or other warninds. Eris could also be a boss. The traveller and the darkness could be super bosses. The worm gods. They might do this thing where we end up fighting the corrupted remnants of races that the darkness has corrupted, like the ecumene race or the races of the harmony. These races could appear as future taken enemies, or merely shells of the ecumene race that have been filled with darkness energy. They are described as angels so that could be an interesting thing to see! Taox could be a boss. So could variks, in theory. But they all pale in comparison to the REAL boss of the series...THE BROOM SWEEPING ROBOT!