There are some 650' rolls of Kodak 3409 on eBay. Reading the spec sheet, it seems to me that it could possibly act as replacement for some other super-slow films that have recently been discontinued. Kodak doesn't show it as discontinued (like 2405) but I don't see it for sale elsewhere.
Has anyone here tried it? That seller has flogged three rolls already so SOMEONE out there is using it!
A secondary question: would any 70mm users be interested (in principle) in splitting a roll? Given the thinner base you can't just judge length by filling existing spools so we'd need some means of counting sprocket holes.