To some extent, 220 film IS a kind of chicken-egg problem. People cannot find 220 film in their suppliers' price lists, so they don't use it (even though they could or would.) This results in low demand, and discontinuation of the product...

I buy my Fuji 220 roll film from Robert White in the UK, and they gladly supply me with that because I buy it in entire cartons (100 rolls), but it is not even listed on their web page, I learned that they sell it because I asked about it.