The MIT economist David Autor helped fracture the old free-trade consensus. But he thinks that what’s replacing it is even worse.

Companies like Alibaba that built China’s world-leading online shopping sector are now helping its sellers find markets beyond the United States.

Small businesses will have no choice but to raise prices, cut staff, delay growth plans or shut down entirely just to keep up with the rising costs of imports they can’t source domestically, one expert said.