If you want to know my personal view on the likelihood of a Civil War happening in the future, I think it's only a matter of time at this rate. You have an entire generation of disenfranchised young men who, rightfully or otherwise, feel that they have nothing to lose. A not insignificant portion of those men do nothing but go to work, the gym, and the range. If the ruling class and their shock troops are successful in taking away those men's jobs as they are starting to be, we will inevitably see a rise in right-wing extremism that will manifest as terrorism and, eventually, civil unrest.
As for the film, I think it gets some things wrong but many things right. The premise of the film is that the federal government is trying to force refugees into middle America, causing individual states to activate their National Guard units. We've already seen the federal government force refugees into states like Minnesota and they've yet to revolt. If anything, the conflict between state and federal government today is predicated on the exact opposite: sanctuary states fighting against the federal government to protect their population of economic migrants from Latin America. In this way, the film failed to predict the future.
In other ways, however, I think it's spot on. The growing divide among ethnic lines, the political class selectively using immigration to help shape electoral demographics, etc. It's also worth noting that all real world exercises involving a modern Civil War result in roughly half of the US Armed Forces defecting immediately, much like in the film. It seems to me like the producers of this film had a firm grasp on the long term effects of globalist economic and immigration policies long before the results of these policies had firmly planted themselves in the public discourse. Perhaps they were fans of Ross Perot?