The COMAC C919 has a considerable amount of American content in it and I'm sure US suppliers would be just as happy to take their money as Boeing's.
Firm orders and bank guarantees are what these companies need to stay in business.
With the recent tariff increase on Chinese imports to the US, getting the MAX flying in China again may be a problem, however these tariffs could be reduced, and Huawei allowed access to Google apps. in return for a CAAC approval of the upcoming Boeing fix.