It's interesting to see that this is one of the longest breaks MM has had from building roller coasters for a while, with the last roller coaster being built being Hot Rod Racers in 2014, and the last full scale one being YOLOcoaster in '13, not counting Twisted Colossus being revamped in 2015.
The last break close to this long was from 1994 (Batman) to 1997 (Superman) (please correct me if I'm wrong oof) and that wasn't even that long. It seems we should be in for a real treat when Six Flags finally decides to give MM (or any other Six Flags park for that matter) another coaster.
*edit: It seems whenever I try to type in "YOLOcoaster" (built in 2013, first top hat and largest loop at the time) the site changes it to YOLOcoaster. It is not a typo