Harmy said:
I don't know, looking at the scene now, it doesn't make much sense in the progression of the conversation - maybe I assumed that, exactly because I thought he couldn't be talking about Luke and it seemed to fit Anakin (even as described in the OT) and Yoda mentioned him before.
Huh, I never got that impression. When Yoda says he looked to the horizon, I pictured Yoda watching Luke's sunset gazing on the farm and his failure to recognize the significance of the droids.