I can tell you what happened.
They shutdown the servers as far as allowing anyone to login. Then they made two or more backups on media that has some shelf life to it. The specific media depends on any laws that specify how long they must keep the data. The laws in question would be statutes of limitations for tort law since no criminal was broken by them shutting down the game. Ever server regardless of its function was backed up this way including the game servers, the login servers (which appeared to be AD based from what I could tell), the websites, code repository servers, test servers. Pretty much anything other than desktops which wouldn't be needed in theory. Of course their business servers like the file servers, domain controllers, database servers, mail servers would also receive this treatment.
How do I know this? I was last man standing for a company that did design work for power plants. I got to do all that work then got to wipe/scrub and remove all equipment from the server room. It was one of the most difficult things I ever did. I worked there for five years. The reason we did the very same thing was due to lawsuits from customers, employees, government entities even competitors.
Our accounts, bases, toons, etc. are likely sitting on tape in a vault waiting on the statutes of limitations to run out. After that, it's off to an industrial shredder.
It is for that very reason I removed my toons about 1 month after the announcement. I didn't want them to have my toons. They do, however, live on in my private wiki as does the base I built for them and various parts of the city they fought in. And I wrote their stories in there too including the withdraw from Paragon City. It brings a tear to my eye writing this post but my toons live on in my mind and in my heart. NCSoft took the city away but they can never take my toons away. I need only close my eyes and I can see them fighting to save the city or role play in the base. When I need a boost, I sit back and ask myself, "What would Flying Snow Mouse do?"
She'd dive head first into the battle and say, "You know, $target, take a bath and get a haircut and people wouldn't hassle you so much" lol