Self publishing has been around for a while. The most notable examples are the underground newspapers and comic books of the sixties. Many of these were printed and distributed independent of the traditional corporate distribution networks, through alternative bookstores and "head shops". Another example is the punk fanzines of the 1980s and 1990s which were distributed through mail order as well as alternative book and record stores. Today with the internet a book or magazine can be sold through a website or social network like Facebook. They can even be sold through e readers or as downloadable .pdf formats, if not straight out blogs. Many major publishers are showing less interest in publishing certain things and that void can be filled by independent publishers. Most American industries have been started with the DIY spirit and there's little of no reason why it should not continue to thrive.
In today's DIY age, people are not waiting on an agent or publishing house to distribute their written work. Self-publishing is also the best way for an author to keep all or most of the profits from book sales. Since more and more people are acquiring certain skills on their own without formal training, the need for books, both online and hard copy, is growing. So, self publishing is only going to become more popular.
When a person self publishes a book or any type of writing, it leaves out the middle man. A person can self publish his own thoughts into words without being told how to write or advertise his or her work. The internet allows more people to freely express themselves through writing and has unlimited audience.
Just because it's easier than ever doesn't mean it will become a booming business. In fact, if it is easy, the demand for publishing jobs will decrease because everyone is doing it.
But the biggest reason it wouldn't become big in the near future has to do with the internet the way it is. Somebody can simply type up what a book or article says and put it on the internet for everyone to see for free. This is why the current publishing business is declining. No one could make money at it, and no one would do it. Unless this problem is fixed, people won't be owning very sucessful self-publishing businesses anytime soon.
It's less likely now than ever. For the big items, people look for what they know, whether you want to acknowledge it or not. A self publisher may have an appeal to a select audience, but that is destined to fade. A central distributor is vital; but however, an entrepeneur can develop that.