Don't wanna write a wall of text, but historically fascist movements have come to power under the banner of a charismatic leader with majority support from the population. As fascistic as America is today, I'm not sure there is enough support to sustain a serious fascist movement. Nearly every major city is at least a 50/50 split among liberal democrats and republicans. Many of those republicans are politically uneducated and don't have a real desire for authoritarian dictate. The Republican candidate has won the popular vote in the presidential election once in the last 30 years and the only places where fascists outnumber every day liberals is in rural America.
So can fascism exist without popular majority support in dense urban areas? What does the fall of capitalism look like with no strong left or right movement? Am I naïve and should we expect reactionary attitudes to grow in response to a collapsing economy? My materialist brain is usually pretty good at seeing the direction we're headed but I'm not sure on this one.
I suppose the doomer take is that we haven't actually collapsed yet, and when the jenga tower really starts to fall, libs will be forced to choose between going right and going left. At that point if we don't have a popular workers movement with enough power, actual fascism will become a threat.
Fascism does not require popular support to exist. It merely needs to support existing power structures of capital.
To that end, support can exist in urban areas. You have to dress it up in protecting property and public safety rhetoric. I've got full blown Hillary-stan in-laws that were extremely against BLM and Defund and pro police crackdown. It didn't even require them to be threatened directly. Footage on the news and fear that it could happen to them was enough.
As for the fall of capital, imo, you can't manage a kind of functioning system. It's going to have to be managed in one of two ways; either doubling down on capitalism or trying to finally move past it which will necessarily require eliminating the profit motive as the economic reason for being.
Economic downturns in modern US history have always led to increases in reactionary attitudes, but it isn't a certainty. When things go to shit, people want a reason for their suffering. They looked to politicians and the news media who were both quick to direct the public's ire away from capital. You see it today with the "Putin Price Hike" rhetoric from the White House. Stoking reactionary fear like this is effective as people don't want to lose what little they have, understandably.
To be bloomer for a moment, the real issue for capital is the unchecked hyper-exploitation that's being created in the millennial and zoomer generations. Doomed to dwindling job prospects, low home ownership, and few with children is a great recipe for people with nothing to lose. The fact that young people are more amenable to socialism is good, but at the same time, dangerous since few have read theory. This opens up lanes for existing power structures to co-opt the idea of socialism, but use it to reinforce themselves.
Capitalism will sell us the rope used to hang it and so on...