This will make little difference. Large number of Chinese sellers already participate in Amazon Prime to get the SEO boost. Shipping through containers to Amazo

This will make little difference. Large number of Chinese sellers already participate in Amazon Prime to get the SEO boost. Shipping through containers to Amazon warehouses is massively inexpensive compared to shipping via US post even if it was subsidized. Only small inexperienced sellers just starting out and tasting waters use US post.