Exactly. He’s telling Luke that he’s going to fall to the Dark Side because, as far as the Emperor is concerned, “it is unavoidable”. Nothing can stop it, he has foreseen Luke defeating Vader and taking his father’s place at his side so he’s letting Luke know that it doesn’t make any difference whether he resists, because it is his destiny.
But doesn’t Vader tell Luke in ESB, “Luke, you can destroy the Emperor. He has forseen this. It is your destiny. Join me, and together we can rule the galaxy as father and son.”
In fact, prior to this the Emperor wants Luke killed, but Vader is the one who suggest he can turn Luke into an ally of the Empire.
We already know the Emperor is a master manipulator and that he sees the future. He deliberately let the Rebellion know where the second Death Star was and that he’d be there. He tells Vader that Luke will surrender himself to him to Vader’s disbelief, and yet, lo’ and behold, Luke does just that. He knows that the shuttle Tyderium was a Rebel ruse. He foresees Luke falling and as far as we’re concerned, we see Luke start down that path when he loses control and attacks the Emperor, which Palpatine sees as Luke fulfilling his destiny to join the Dark Side and replace Vader. If anything, that makes him a better villain: he’s spot on about everything so far, and then even Luke seems to fall into his trap.
The aspects you mentioned, like foreseeing that Luke will go to Vader, are good traits of a villain. You think this guy is one step ahead of your every move. But in his attempt to turn Luke, it was incredibly stupid, and that goes beyond simply being overconfident. And not only that, but other factors are at play which make me feel he’s one of the less interesting villains out there. Maybe if we didn’t see his eyes, like in The Phantom Menace when he was talking to the Asian stereotype aliens via hologram, and he had that same gravitas in his voice in that film, then he would come across more mysterious and intimidating. I prefer Frank Langella’s Skeletor from MOTU film over Palpatine. Better dialogue, better delivery, and better look.
Like Density said, the only reason his plan failed was because of his overconfidence and underestimation of the Rebel resolve against the Empire, Luke’s resolve against the Dark Side, and finally (as well as fatally) Vader’s resolve. When Luke defeats Vader, realizes where he is headed if he continues, and throws down his weapon to show that he is truly a Jedi, the Emperor realizes that he needs to up the ante, and so he tortures Luke in an attempt to break him, to turn him to the Dark Side by Force (hur hur). Again, he was overconfident in his ability to do so, in Vader’s allegiance to the Sith and his master, and he underestimated the good inside of Anakin and the love a father has for his son.
That’s how I see it at least.
Like I said, he comes off like a cartoon villain, in the same way that the cheesy villains tell the hero their whole plan before killing them.