Hamilton's success has been the result of its ability to connect with a varied audience. Different generations and cultures are united by the link between modern music, a diverse cast, and a story of American History. While this is unique, it is not impossible to replicate. As culture changes over time, there will be future opportunities for writers to connect to their audiences in an equally great way.
Hamilton was innovative and different. It took the art form of rap and incorporated it with history, giving new life to a dry subject matter. People are flocking to see it in droves. I do believe this feat can be repeated, which i'm sure will happen. It captures the attention of the people including younger patrons who normally avoid the arts. You can't beat that.
The play Hamilton was wildly successful on Broadway. It was a hip hop musical about the former president Alexander Hamilton. However, there are lots of plays that have been super popular on Broadway. Looking at shows like Cats, Les Miserables, or Wicked, one can remember how popular a play can be. I am sure there will be another in the future that is just as amazing.
Musical theatre is somewhat of a niche and not enjoyed by much of the population. Hamilton has brought in a fresh, new flavour to Broadway which may well change the future of musicals. Many see the musical theatre as camp, dull or dated Hamilton has given it a harder edge and a more modern feel. A new audience may mean repeated success.