Many shows that are now revived are part of a legacy - one that spans many decades in the theater and dictates the initial future for new works that will be presented. In the last 20 years or so, modern theater has gathered it's own legacy, one which will change the way we perceive theater, at least initially.
Shows such as Hamilton drastically changed the bounds of what could be done in a musical, while long running shows like Wicked have cemented the book turned musical adaptations. Jukebox musicals have become a standard, whether they display the artist's life or use their songs to craft a story. Other shows such as Come From Away draw from true events to create uplifting and poignant stories, while plays like Straight White Men are asking big questions about things like privilege.
On the flip side, revivals have taken on a new shape. Shows such as The Boys in the Band and Once on this Island have been "dusted off" and greeted with much acclaim. Other shows that have become staples in the revival category like My Fair Lady have taken a new approach to important issues in modern society, such as #MeToo and allowed the story to flourish in a world that is more conscious to these issues.
The legacy of today's theater may not be for sweeping melodies or even great writers. It will instead be one for pushing boundaries, questioning society, and working to be in sync with movements that will change the world.