Chinese FDI inflows and outflows are actually almost equivalent in USD terms. Furthermore, China is well known for placing huge restrictions on capital outflow in its economy.

I think it's safe to say that even if every last dollar of FDI dried up, China would be more than fine with its domestic capital supply.

Furthermore, the identities of the big FDI investors are dominated by physical manufacturers investing in onshore operations. Not so much liquid global securities trading.