I'd be sad to see Nissan go.
I have no idea how Mitsubishi hangs on; they're just too small a player now. What they really should do is get out of the car business, and jump into the airliner business. The market is screaming for alternatives to Boeing and Airbus. Boeing has proven itself untrustworthy, and Airbus just doesn't have the production capacity to handle increased orders. On top of that, I'm sure ANA and JAL would love to buy domestically-made airliners if they could.
Of course, the US may sail in and prop those two up. Kind of a "Too political to fail" type thing. But on their own, absent help like that, yeah, I don't really see how they make it without some sort of market event. Failure, fire sale merger, etc.
Vietnam doesn't really care too much about WTO rules, so they provide not only enormous resources to their firms through the back door, but also slap enormous tariffs on foreign auto dealers at the front door.
So yeah, what we may term unfair advantage, they call command capitalism.
For various reason I believe FCA, Nissan, Mitsubishi and Ford are going to fail.
I can't imagine any upstart without any compelling unfair advantage/killer product is going to fair well in an imploding auto market.
If he started this endeavor 8-10 years ago, he'd have an advantage. Now nearly every car maker is either producing or on the verge of producing at least one EV model.