Europe could be pretty self sufficient as well, but it chose to engage in trade for the benefit of both sides and also as a way to make war more difficult (very explicitly in the case of German energy imports)

Some things will definitely get more expensive in the short run, but on the positive side this will speed up transition to renewable energies and less food waste (through animal production etc).

But in the end most of the goods will probably just be shuffled around though. China will import more wheat from Russia at slightly lower prices while the current non-russian suppliers will export to the West at slightly higher prices.