I don’t think so. The average fan may not know who Thrawn or Ezra is. Showing them in the last 10 minutes isn’t enough to get people to continue watching. They’ll reveal them in this episode or the next and use Thrawn’s appearance to show just how big of a threat he is. Someone may die. Then the series will end with Thrawn making his way to the original galaxy, making us intrigued as to what he’ll do when he’s there.
Without showing him enough, no one will feel that he’s a threat (without prior knowledge of him), and no one will care that he gets back to the main galaxy.