The losses are likely to be larger for the US than for China, because Chinese imports from the US include a larger share of agricultural commodities for which alternative suppliers are relatively easy to find. For example, China can import soybeans from Brazil instead of the US, at little additional cost. Moreover, Chinese countervailing measures have been more moderate; there is little prospect of a blanket 25% tariff on US imports.
All in all, the Sino-US trade war may lead to some losses for China, but those losses will likely be dwarfed by the costs incurred by the US itself. Meanwhile, the rest of the world may well have reason to wish both sides a long and fruitful conflict.