Nearly all the critics and literati thought him a hack because he wrote for the common people.
A myth, James. His players were referred to as “His Majesty’s Servants” or earlier as “the Chamberlain’s Men” and the principals enjoyed a high status at court. Remember, they also did command performances at Whitehall Palace. And the Globe was patronized by both the nobility and commonality. It was a later age that dismissed him, not his own, and he went out of fashion for a long time.
Future classics? It’s always pure guesswork but my guesses would be Tolkien’s Lord of the Rings , Bradbury’s Fahrenheit 451 , Martin’s Game of Thrones and very possibly his currently under-appreciated Fevre Dream . Possibly some of King’s early work such as Salem’s Lot. It was much less self-indulgent than his later work. But who knows what future centuries will appreciate and enjoy? So chances are, we’re guessing wrong.