Last May we learned that the 500 euro note is being completely eliminated, and just a few weeks ago the European Commission released a new "Action Plan" which instructs member states to explore "potential upper limits to cash payments". In the name of "fighting terrorism", this "Action Plan" discusses the benefits of "prohibitions for cash payments above a specific threshold" and it says that those prohibitions should include "virtual currencies (such as BitCoin) and prepaid instruments (such as pre-paid credit cards) when they are used anonymously."
This new document does not mention what an appropriate threshold would be for member states, but we do know that Spain already bans certain cash transactions above 2,500 euros, and Italy and France already ban cash transactions above 1,000 euros.
This is a perfect way to transition to a cashless society without creating too much of an uproar. By setting a maximum legal level for cash transactions and slowly lowering it, in effect you can slowly but surely phase cash out without people understanding what is happening.