Seeing as how Picard had several run-ins with the Romulans during his time in Starfleet and tried to stop the mounting tensions between the Federation and the Romulan Empire many times, it’s possible that the destruction of the empire is the “unimaginable” event that the narrator is talking about.
In early January of this year, Alex Kurtzman, Star Trek: Discovery’s executive producer and showrunner who is also working to develop Picard, spoke out and said that when the series picks up, we’d see a Picard who’d had his life “radically altered by the dissolution of the Romulan Empire.”
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