Most importantly, perhaps, the trend to factor equalization—although not proven, it is easy to see rising wages in China or Mexico, for example—creates a new optimization problem for MNEs with GVCs whenever a company undertakes periodic strategic reviews of its cross-border structure.
Such reviews can lead (and have led) to decisions to re-shore parts of the supply chain back to the home country—in short, the optimal supply-chain arrangement can vary considerably over time as underlying conditions evolve. This means that the degree of integration may also vary significantly over time, in both directions, making it risky to treat it as a permanent state of the world.