Paul looks at the faces of these elders, and a profound certainty settles upon him. He knows, with a deep and certain conviction, that this is goodbye.
When Paul says, "I know that ye all... shall see my face no more," he isn't just expressing a sad feeling. The context suggests this knowledge came from the Holy Spirit, as he'd been warned of suffering and imprisonment awaiting him in Jerusalem (Acts 20:23). This isn't a vague premonition; it's a confident declaration based on divine revelation about his future path, which he believed would lead to his death.
While scholars debate if Paul literally never saw anyone from this specific group again, or if he simply didn't expect to see them in that region due to his impending fate, the core message is Paul's conviction that his ministry in Asia was concluding. He speaks with a sense of finality about his personal interactions with this community.