The reason might rather be that it doesn't make sense to purchase an aircraft passengers are reluctant to fly with. No matter how well the problems of the 737 8 MAX are resolved, its reputation is tainted. Every further accident of that type will be blamed to Boeing.
It reminds me a lot of the DC-10 in the 1970s.
Boeing will probably have to rename the 737 8 MAX and marketing it as a brand new type.