Well this fall 2017 season will be the end of star wars rebels. The head of production said that when we see X wings we see the last of the show. And at the end of this last season they were 2 years before the events of Rogue one and A New Hope. This new season will make it one year. They can't touch the movie's.
But Disney has invested in Rebels, I expect them to keep going in some new form. For example this year comes The Last Jedi, 2016 was Rogue one, 2015 was The Force Awakens. So what is 2018? Well presumably Han Solo but then 2019 episode 9 and in 2020? They want to milk star wars for all it's worth and a Rebels movie is a good option.
And I would lay money down that by the last episodes of this coming Rebels season they will start production of a new Star wars vehicle for XD.