The more likely problem will have to do with a US or Chinese company buying an EU company (given the scale imbalances in question). It'd be critical to maintain the existing GDPR compliance and keep the entities separate if the US or Chinese operations are not GDPR compliant per their domestic businesses.

Alibaba for example likely has no plans to concern itself with GDPR compliance in its domestic Chinese operations. They obviously will segment and comply with GDPR as it pertains to the EU operations / EU customers.