If you want to look at the data on what types of items are being exported/imported between china and the us, here's a good link.
http://www.oecd.org/document/8/0,2340,en_2825_293564_35833096_1_1_1_1,00.html
If you look at the items, Chinese exports for the most part have ready substitutes. Chinese imports, if you assume the west doesn't splinter, are highly vulnerable. More and more Chinese imports are coming from east asia. Depending on how those fall out, the Chinese economy could be really hurting.
It's not just the gross dollar amount of imports/exports that is relevant, it's replaceability with alternate suppliers that's critical.