Is the United States heading toward collapse and potentially a new kind of civil war?

One cannot really predict the future of nations. I suspect terms such as collapse and civil war are overly dramatic. Many of the fractures in current civic society in the United States do exist along lines of age, race, ethnicity, gender, and education, with younger people, women, LGBTQ people, college graduates, and ethnic minorities tending to be more liberal, and less educated, older, white, and male voters tending to be more conservative. Demographic projections suggest that the more liberal group will, over the next few decades, become the majority of voters. In many ways this is reassuring from the perspective of the trajectory of America's role as a world power.
Although terms such as "collapse" may be overly dramatic, the current course of the United States could be described as a decline compared to other developed countries. While all other developed countries have some form of universal health care, the United States lags behind, meaning that it has higher infant mortality rates and lower life expectancy than other developed countries. The lack of affordable health care has a negative effect on the workforce and discourages entrepreneurship by linking health insurance to certain types of employment. The net effect is sticking people in an old economy rather than easing the transition into a new economy and thus leading to a relative economic decline.
Trump's abandoning of the Paris climate accords, combined with his re-introducing of Republican-led subsidies and trade supports to old-economy industries, such as steel, and polluting sources of energy, such as fossil fuels, harm the long-term prospects of the United States as an economic power; as other countries race ahead in developing renewable energy, the United States is pursuing a backward looking industrial policy. The abandonment of the Paris Agreement also has had a geopolitical effect of decreasing the role of the US as a world leader, with China and the EU stepping in the fill the vacuum.
Rising economic inequality and anti-immigrant rhetoric also stoke internal tensions within the United States. However, younger and more educated people are generally more comfortable with immigration, more open to LBGTQ issues, and less racist than older or less educated people. These demographic trends suggest that many of the current political tensions will decrease over the next 30 or 40 years; although, the transitional period may be difficult.
https://www.citylab.com/life/2018/03/the-unhappy-states-of-america/555800/

https://www.nytimes.com/2018/04/21/opinion/sunday/adapting-to-american-decline.html

https://www.pewresearch.org/fact-tank/2016/04/15/americans-views-of-immigrants-marked-by-widening-partisan-generational-divides/