By using Bitcoin. They'll realise they're late to the party soon enough.
So how long will it take for them to be late?
I mean unless they are losing a lot of bussiness because they haven't adopted bitcoin, they aren't really late. And then they also need suppliers to use bitcoin...
As I said above: as long as it is volatile, it won't be used as currency. Electronics retailers only make a few% profit nowadays. They can't take the risk of even a minor 10-20% drop in value as they need to pay the suppliers. Same for the suppliers. Owning a store and selling things is a whole different thing compared to investing in volatile currency or stocks.
When is the last time you went to the Apple store and tried to buy a mac with an APPL share?
Only shops that have either obscene mark-ups (glasses!) or shops that sell digital goods can take the risk, but even they will need to pay their employees in cold hard cash.