The Tomorrowland Speedway at the Magic Kingdom will close for five months in 2019 as the ride’s track is rerouted to make way for TRON. The Speedway is expected to close January 2, 2019 before reopening to drivers on May 18, 2019.
The concept art for the TRON coaster at the top of this page shows that the Speedway will sit quite close to TRON once the projects are completed. Rerouting the track now will allow for more construction to begin. To date, the only construction seen for the TRON ride has been some land clearing.
Previously, Disney stated that the ride will reopen as the same ride guests know now, but with an altered route to make room for the new TRON coaster. However, rumors suggested that the Speedway might be rethemed closer to the opening of the TRON coaster in 2021. Disney has not confirmed any retheming to the attraction, but it would be odd to see gasoline-powered cars running so close to the new ride that has a very futuristic and clean atheistic.
Source: WDWMagic