What Does a Win Over Thurman do for Pacquiao?

A loss wouldn't hurt Pacquiao's legacy at all. But a victory might impact it in my opinion. Manny Pacquiao is 40 years old and we all know the great feats he's accomplished. He's in the twilight of his career and doesn't need these sort of fights. But here he is in the final chapter of his illustrious career. He was HOF worthy in '08 when he beat the likes of Marquez, Barrera, and Morales. He went on a glorious run from '09 to '15 and now he's here facing a new generation in Keith Thurman. Thurman is a top 3-5 welterweight, a world champion in his prime, stronger, younger, and has never tasted defeat. What would a win do to Pacquiao's legacy? As I mentioned before, Pacquiao's legacy is already cemented and nothing can take away what he's already done. He could lose and still retain his legacy. But a win would surely do something for his legacy. Whenever Pacquiao fights at this stage of his career, I feel like his fights are no longer about moving up in the current P4P rankings or top 10 rankings of a division. No. At this stage, whenever Pacquiao fights it moves the needle on his status on the list of all time greats. What do you guys think?