Six Flags Magic Mountain:
2017: Flat ride package with Larson looper, flyers, and Mack Twist & Splash
2018: Justice League dark ride on former amphitheater spot
2019: S&S Gale Force or Zierer tower coaster in former Deja Vu spot
2020: 400 ft SkyScreamer in Sky Tower spot or Cyclone Bay
2021: 50th anniversary celebration with redesigned entrance and plaza
Disneyland:
2016: Luigi's Rollickin Roadsters, Soarin' Over the World, revised MyMagic+ testing begins
2017: Full MyMagic+ rollout, eastern parking structure opens, Paradise Pier Hotel closes, DTD revamp begins
2018: Aesthetic changes to Hollywoodland and Paradise Pier, Star Tours rethemed
2019: Star Wars Land opens, new Grand Floridian-esque hotel in former PPH site and adjacent parking lot with small indoor water park, DTD revamp completed
2020: Nothing major
Busch Gardens Williamsburg:
2017: New area themed to Spain or Greece south of Festa Italia with RMC/GCI/Gravity Group/Intamin woodie
2018: Funtime starflyer in Ireland, Loch Ness Monster restored with Vekoma trains and special effects in tunnel
2019: Water park expansion
2020: Minor improvements
2021: Scandinavian area with large indoor section and Mack suspended dark ride
Just registered on the forums a few days ago, long time reader but first time poster.