I don't think Scion's going to make it that far. He's got apprentice (e.g. master and apprentice) written all over him. He's a brute, and the flashy brutish guy who likes to show off is always inferior to the thinking man/woman behind the scenes. Malak was Revan's inferior in tactics and, thusly, intelligence (cunning, machinacity [sic], whatever you want to call it) and ultimately paid the price for taking on the throne. Scion's in the scary meathead mold of Vader, Maul, and to a much lesser extent, Tyranus.
He's the muscle, not the mind.
He's the Mandalorian war Malak to Nihilis's Revan.
He's Sagat to MSG's M. Bison.