Nissan is in trouble in North America-without a doubt. There are many vehicle manufacturers that sell in other parts of the world and not in North America anymore. Fiat, Peugeot, and others once sold here who left who still sell elsewhere. Car companies are not known for floating the U.S. sales with profits from elsewhere.Ford is very N. America centric. Ford sold 4.5M worldwide. Almost half in N. America.
Nissan sold 3.3M, less than 1/3 in N. America. Ford and Nissan really don't compete - maybe around the edges. Nissan is very popular in countries you wouldn't find a Ford. This is why I do not believe Nissan will go under. There popular in markets that are still growing. They have just been very poorly managed for a long time.
Ford also has 3X the debt - but no one talks about Ford going under.
As a comparator - Toyota sold almost 11M. Total global market is 90M.