Since 2022 the single most important line item on any Europe to East Asia route has not been fuel hedging or aircraft type. It has been permission to fly over Siberia. European carriers lost it under sanctions and retaliation; Chinese carriers kept it. The result was a structural cost wedge of two to four hours of block time, extra fuel, sometimes an extra crew, on exactly the routes where the two groups compete head to head. That wedge is why British Airways dropped Beijing, why Lufthansa cut Frankfurt to Beijing, why Virgin Atlantic left Shanghai, and why Finnair, whose entire hub logic was the shortest great circle route from Europe to Asia, spent three years rebuilding its network around the Atlantic instead.
Ukraine's stated goal of shutting down Russia's commercial airspace changes the variable that has been treated as fixed. The mechanism is not a formal ban. It is the accumulation of temporary airport closures, ground stops and rerouted corridors that follow long range strikes, and the war risk and reinsurance response that trails them. Airspace does not need to be legally closed to become commercially unusable: it needs underwriters to price it, safety regulators outside Russia to advise against it, and boards to conclude that a hull loss over Siberia is not worth ninety minutes of fuel. Once third country operators start planning around Russian airspace, the shortcut stops being an asset that only one side holds.