It's only February 2019. Tron also contractually CAN'T open in WDW until June 16th 2021 or later since Shanghai has a 5 year exclusivity. If they had to push the opening of this out to fall 2019, that's still about 32-34 months from now. It's a simple launch coaster with the toughest part of the build likely being the canopy. They should be fine.
Definitely a much more complex build for Guardians, but they're already so far along that it does boggle the mind how it's gonna take until 2021. Of course the UoE building is literally nothing but a giant shell right now, so the queue and load platforms have a LONG way to go.