they can get bitcoin in paper form like what you get when using Bitcoin ATM.
pieces of paper with public and private address after that they can import the private key to any wallet "just show the private key to any scanner" and get the money.
Important point
you must have some knowledge and internet access to use bitcoin.
thats it,although i dont believe that this thing will happen,still we must be ready in regards of bitcoin as a total mode of payment..things like this are the main concern of satoshi why he created his for the people to easily access all part of payments and service in just one click,but ofcourse the problem to face. Is those whos not ready for the changes like this