Thank you for this great discussion!
It has led me to think, (maybe even to realise, if my thinking is correct) that since a lot of what people "need" fiat for is basically commodities.
Thus possibly my long ago ideas about how things like milk and eggs and butter and sugar and so on would probably be a whole lot cheaper if lots of folk bought subscriptions, so the shops would have a more certain estimate of how much of each thing they need to have in stock by what date and conglomerates or chains of shops could use commodities markets and future-commodities markets more accurately and so on.
Admittedly milk and eggs and butter are, like fiat, perishables in the sense that like fiat they can be expected somewhat reliably to lose value over time unless sufficient preservative techniques like fridges or interest-bearing savings accounts (and at some inflation rates not even that latter) are used to attempt to at least slow down the rate at which they "perish", but as they lack the flexibility of fiat (vast libraries full of recipes using them notwithstanding) thus can possibly be provided cheaper than fiat can be provided.
Part of my reason for suspecting that last part is that for centuries providers of milk eggs butter and such have not only earned themselves profits as measured in fiat but have in fact as far as I am aware everywhere world-wide over those centuries earned more and more and more fiat per unit of milk eggs butter etc.
Thus maybe buying up actual farms and such, with a sufficiently long-term view to just keep on producing such commodies to sell for a fixed amount of bitcoin per unit of each commodity (at least to members; obviously non-members will be prone to buying elsewhere using fiat during periods when fiat is in a bubble relative to bitcoin) knowing that over time bitcoin will recover from any apparent dips in its value-in-fiat, could be a reasonable concept to look into. Subscription based sales would likely be important in such ideas so that even if members are tempted to buy their groceries elsewhere using fiat who cares, they already paid for what the bitcoin-based producer was producing for them so if they don't show up to pick it up that is okay, all the more to sell to other members who randomly happen to want more than they subscribed to.
I know, this is very nebulous and vague idea so far but ultimately boils down to the same old same old more vendors accepting bitcoin would be helpful; it is just that it addresses the common barrier wannabe-such-vendors run into of where though are they to obtain wholesale using bitcoins the things they want to retail...
-MarkM-