A few issues here though
the Great Depression is a great mess, the Bonus Army doesn't get anything from Congress and the Bonus Army and MacArthur gets super ugly
Coincidentally, MacArthur did use force to disperse the Bonus Army (well... non-lethal). Plus the Bonus Army were unarmed veterans and their families protesting the lack of reparations for their service in WWI. So the riot that'd ensue would be relatively easy to quash.
By the Bonus Army? Because they and MacArthur's troops would be villainized for going that far.
the White House is hit Hoover is killed, the shook gives Curtis a massive heart attack
Hit with what? If the conflagration got the White House I get it. But would Hoover and Curtis croak? Well, maybe the ill Curtis from the stress of escaping, but Hoover would most likely be evacuated to a safer spot.
next in line Secretary of State Henry L. Stimson is in London at the time, Congress has left to get away from the fight
All of congress? I'll be the first to admit that they'd get out of there ASAP, but in the bedlam the city's going through, they'd have issues in escaping. And if they do... Why can't Hoover?
Chaos reins over DC and the nation, Riots are in almost every major city in the US
The US wasn't Weimar Germany. Plus that's pretty drastic.
MacArthur is shot by an Anarchist during the fighting, Eisenhower takes over and quickly looks for a Civilian to take orders form the only member of the Federal Government left in the City is Chief Justice Charles Evans Hughes who takes control,
What about the White House Cabinet? Because they supersede the Chief Justice for a good while. Plus in a dire situation like this? Eisenhower probably wouldn't be the highest ranking officer here, plus he'd take care of the immediate threat to the city first. MacArthur I could see getting shot though.
his strong leadership brings America under control by the time President Stimson reaches DC, many Americans feel law and order has broken down, in the lead up to the 1932 election the Rich and Powerful, fearing FDR as a Communist turn to the now power Chief Justice and an angered Colonel Patton,
Just so you know... it was the Republicans that would probably be beaten even more in this situation where they crack down on the protesters. Oh, and I'll just go and say that Patton would never go into politics.
shortly before the election FDR is killed by Giuseppe Zangara(wether this was random act or part of the Coup is unclear) with the death of FDR is was easy for Patton, DuPont, and Hughes to over throw a weak and shell-shocked President and push the coup and Law and Order government changes on the grieving people
First off, why would Zangara go after FDR? He was going to kill the president, not him. He believed that Hoover was the cause of his problems, and when he died, would probably go after Stimpson instead. Second, Patton was a Captain by this point, and wasn't even in the area at this point. Finally... which DuPont? Because there was more than one of them. Plus seeing as they're trying to kill the constitution, the people probably wouldn't role with it. Better yet, I don't think they would trust a military installed dictatorship with just these events.
You didn't even cover the equality issue and the harsh laws.
There's a reason I went with ASB.