Stage 20 of the 2017 Tour de France is a 22.5km ITT around Marseille. While there are no categorized climbs, there is a bit of a hill up to the Notre-Dame-de-la-Garde cathedral. Otherwise, the route is fairly flat and set on urban roads. The start and finish of the stage takes place inside the local Velodrome.
The past ten years, there has a been a tradition of the yellow jersey holder winning the last ITT. Since Froome has yet to win a race this year or a stage in the Tour, he will most likely be determined to repeat that trend. Playing in his favor is the statistic that only once in the past ten years has the yellow jersey at the start of the ITT not been the same rider at the end of the day.
The shortness of the stage will make it difficult for gc guys to gain significant amounts of time. However, with the gaps between the top 3 very slim, there could be a shakeup if Uran or Bardet ride an incredibly solid ITT.