Thats just standard Star Wars trope. Master, villian, apprentice (they are always teenagers. I guess they bring in the monies). Which was been played to often imho. But the master has to die so the apprentice can go forth and do stuff. Which is in many things and for a long time, but it would be nice for something different.
You knew what was going to happen as soon as this was said.
Gorion : There is something wrong. We are in an ambush.
The Villian : You're perceptive for an old man.
Anyways Vader/Malgus/Emperor(s) needs to retire for a bit and bring in something new. A nervoius sith lord. I dunno.