In Europe, experienced travelers get cash from ATMs and avoid using credit cards. Helping to drive this practice was the fact that most U.S.-based credit cards lacked the chip & pin combination used in Europe, which adds a tiny degree of hassle when using a credit card over there. Although we're now getting the "chip" part in our cards, our banks have generally opted to retain signatures instead of mandating pins, so the practice of relying on cash still stands. But what happens when other countries really stop using cash? This New Yorker article gives a pretty good idea of what may lie ahead: Imagining a cashless world. (Note the side benefit of the drop in street crime when people stop carrying cash.)
I should hasten to note that this change has not hit the major European countries yet and that the advice to use an ATM/cash combo still is good, so don't panic if you are headed overseas anytime soon. Still it is interesting to consider how things will likely change in the not too distant future. Of course, by then we'll probably be buying everything with our phones anyway. (Potential trouble for those who shun taking a phone as a traveling companion.)