My games from hereon-out will be freemium or heavily DLC-supported. 
Have been thinking about this more often now.
To just release the game part for part, chapter for chapter, something like that.
reminds me of Siren Blood Curse, which I bought the whole game as BD, cause the chapters where extremely overpriced; or even Starcraft 2 which doesnt ship the whole story with the first game.
Yeah just a buck or two per addition. Even $5 is usually too high, in my opinion.
I hear you can hire an armada if you have a pirate problem …
Any who an offline game will have problems (Hell look at steam games … you can get them for free if you look hard enough)
But if you require a user account … that has paid access then your talking more DRM.
Its easy to throw in some encryption and tweek it so its difficult to break. The time spent on reverse engineering a mutating key encryption will be enough to keep most away. Then they would have to reverse engineer communications. That’s made difficult my nonsensical communications. (For example instead of saying Move player X to (X,Y) say YG8sug7, G(&IHHh, or ^&ygf … yes you can make the same data appear different! at different times) Hell throw in some false data to throw them off too!
Eventually it will be broken someone will make a server and people will be playing for free, the only counteraction to this would be having:
A) popularity in the MMO way (people would rather play with each other then by themselves if the games is designed such)
B) Have the main content of the game stored and executed on the server (Eg a quest the story etc)
C) Making enough money to not worry about it
Regardless of what you do, as others have stated … you have 99 problems and a DRM aint one.
(Ha on that last one … I need sleep)