The Tower of Terror will be replaced with Guardians of the Galaxy: Mission Breakout next year. Disney Parks Blog announced the last day to ride the Twilight Zone attraction today. January 2nd, 2017 will be the last day to go to the 5th Dimension. Before then, starting September 9 to October 31 for Halloween Time, Tower of Terror will have a “Late Check Out” mode after twilight. The attraction will be in complete darkness for guests to experience it in a different way.
The original parks blog post can be found here.