To make this idea more clear, here’s what I’m thinking.

“What are you doing here?”

“I saw myself on the dark throne. I’m never leaving this place, I’m doing what you did.”

“I was wrong. I feared I’d only push Ben toward that fate. What are you most afraid of?”

EDIT: This would then explain why we have a scene earlier of Luke talking to Kylo. He’s confronting his fear, which is the “destiny of a Jedi”. See how everything comes full circle? 😉 And it still works in the context of TLJ alone, as he wanted the Jedi to end so that the dark wouldn’t be as oppressive or retributive. Same concept, just in a slightly different context. So not a retcon, especially compared to what was there originally.