If China pays less it just means the above situation works out to China's advantage even more than with my toy numbers, and even less to Europe's. Regardless of what numbers you use, Europe loses more than Russia. Sanctions only "work" (by the very low standards of workingness they're held to) if the sanctioned party needs to sell a lot more than the sanctioner needs to buy. With Europe that's clearly not the case - Russia can easily sell to others but Europe faces more or less immediate collapse. The advantage here is Russia's and the inability of the EU to recognize that they miscalculated threatens its population with dire levels of deprivation of economic destruction.