Federer wins the Basel Open for the 10th time and does so without going to a 3rd set and one walkover, which should mean he's quite fresh for Paris. Even if Djokovic wins in Paris - he'll drop to No2 with Nadal taking over the No1 ranking, a good run to the final should make him likely to keep that to the year end.
In qualification for the Year end tournament, Nadal, Djokivoc, Federer, Medvedev, Thiem and Tsitsipas have all qualified. Zverev in the next spot should qualify to defend his title but it's tight after that - though Berrettini is most likely.
In the WTA year end, Barty is, I think, certain to finish No1 no matter what the results. It's very tough to call a winner here though I wonder if Andreescu might finish a spectacular year with a win.
ETA, looking at the points available in Shenzhen, Barty isn't quite guaranteed No1 ranking yet, but 1 more victory will do it.