Dry cask storage is simple, relatively cheap, and forecloses no future option for dealing with waste. By the time the waste is so cooled off it is no longer self protecting from amateur diversion of plutonium -- maybe 300 years -- options should be greatly expanded for its disposal, including shooting it into space on dirt cheap extremely reliable launchers.

In any case, setting the fuel disposal cost to zero still leaves fission uncompetitive, given the cost of building new nuclear power plants. This is especially the case if one imagines a nuclear powered world economy, which likely would have to resort to some flavor of breeder reactors. Reprocessing would be necessary for breeders, but that wouldn't make breeders cheaper than current burner reactors.