I personally think DRM is a passing fad in the industry and it will probably go mostly extinct within 10 years. DRM tends to just piss the consumers off too much and causes people to not buy a product. This has been seen with audio CDs. It is only going to be worse if people start buying things they can't copy, or that will disappear or potentially be unusable in 5-10 years. DRM also inhibits fair use far more than is even remotely reasonable. Lastly, any DRM made will eventually be cracked, rendering it useless.
And heck, what does DRM really stop anyhow? Studies show that people who download pirated files largely are influenced to buy more than they otherwise would. There is almost no evidence that piracy has harmed the industry; instead the industry has just blamed piracy on its own failings. Eventually the industry will adopt to the new higher tech market, and hopefully that will involved it churning out less crap (which is one of the reasons why some industries pursuing DRM have actually done bad). Right now industries pursuing DRM are acting like consumers are idiots, but they aren't idiots and the consumer knows that if he doesn't pay for a product, then he is unlikely to get more of that kind of product in the future. This is certainly part of why everyone I know that pirates tends to buy the software they pirate--the exception being if the software is garbage, but that stuff shouldn't do well anyhow.
In short, there is no good reason to have DRM and plenty of reasons not to. Sure, there will be some files that are used by more than one person, and there will be the occasional freeloader who hardly buys anything. These are more the exception than the rule.