At the start of An Inspector Calls, the characters form a hierarchy, with Arthur Birling at the top and Eva/Daisy at the bottom. Priestley uses the events of the play to rearrange this hierarchy. How do things stand at the end?

The play has a double ending that creates a sense of deja vu . First, the Birlings learn that Eva/Daisy hasn't killed herself and feel greatly relieved. Once they are off the hook, they show they have, by and large, learned nothing, for they seem to be willing to go back to their old ways. Even with what they now know, when they find out Eva is alive, they don't rush off to help her.
Then it happens—perhaps because they didn't rush off to help her—that Eva does commit suicide as Inspector Goole described. He is seemingly a supernatural being who warned them of what was to come, but they paid no heed. They once again hear the knock of an inspector at the door, this time for real.
At the end of the play, the Birlings can no longer feel insulated from the damage they have caused. They have been willing to be cruel to Eva because they never saw any negative consequences to them for being so—in fact, they gained an advantage from it. By firing her rather than giving her a raise, Mr. Birling scared the other employees at the factory into not asking for raises. When Sheila had her fired from a department store for rudeness, she benefitted because other employees were now intimidated into groveling to her. When Eva was unemployed and desperate, the men could take sexual advantage of her, and Mrs. Birling could feel self righteous and powerful in turning down her request for charity.
Now, however, the tables have turned, and it looks like the Birlings might be held accountable for the young woman's death. Now they might learn what it feels like to be on the bottom, having to beg for mercy, rather than to be on the top, kicking down the people below them. It is possible that if they have to suffer, they might learn some compassion. Certainly if they don't, we as an audience should.