@weebdeluxe I was recently selling at a flea market, and on a whim I wrote out "3DS STREETPASS HERE!" on a piece of printer paper and taped it up above my tables.
I had people photographing the sign, messaging friends about it, and pulling their 2DS or 3DS out of bags in order to turn on the WiFi. Got 5 new StreetPasses that day.
I think a lot of people still have their devices, they just need a reminder.