There are a couple of attractions at Walt Disney World Resort© that will be closing for early 2019 due to projects or refurbishments. These were announced or are anticipated to be announced shortly.
Animal Kingdom - Kali River Rapids: Guests with scheduled Fastpass+ selections for this attraction in early February received an email this week that a substitute selection was made. We've learned the attraction will close Jan. 7th through March 22nd, 2019.
Magic Kingdom - Tomorrowland Speedyway is closing in early January through mid-May 2019 as park of the track is relocated in preparation for a future attraction (Tron).
Magic Kingdom - Walt Disney World Railroad: the train is currently parked in the train station through the summer. Again, this is due to the upcoming Tron attraction.
Epcot - Test Track: I anticipate a refurbishment will be shared soon as it is unavailable for early February Fastpass+ selection.