1) Bitcoin, right now, is a little bit more "digital gold" than "digital cash" only because of PRICE dynamics (not affected by inflation, monetization driving appreciation, gresham law discouraging spending it instead of fist if not necessary), NOT at all because of tx COSTS!
2) Tx costs for ANY form of "cash" known in human history, while often trivial in face-to-face txs (except for verification costs, often quite high), are always orders of magnitude higher than non-cash scriptural money in every case implying distance or complex interactions.
3) W/ Lightning Network & other trustless scaling solutions, as well as w/ the trusted ones, Bitcoin will be even LESS similar to physical cash, because its transfer over significant distances will be almost instant & almost free, a typical feature of NON-cash scriptural money.
4) It will still be a form of "digital gold" because of all the reasons listed in 1), but it will be used, when fiat cannot be used, in fast/micro txs between parties far away from each other, which is typically IMPOSSIBLE for legacy physical cash, expensive & slow to move.
5) The reasons Satoshi (& before him Nick Szabo, Wei Dai, Hal Finney, Adam Back, David Chaum, etc.) all used the term "cash" for what they were looking for, was NOT cheap/fast trasfer across huge distance, which is a very un-cash feature, but limitation of counterparty risk.
6) For the goal expressed in 5), the analogies of "digital cash" or "digital gold" were indeed PERFECTLY INTERCHANGEABLE (ie: "bgold"). The only meaningful difference, outlined in 1), was not considered back then & is all about monetary considerations, not scalability ones.
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