Not the end of the world!
Youve got to ask yourself whqts the competition.
Tickets -- ie bits of paper with unreadable print.
pretty easy to forge but nobody bothers?
Bits of cardboard with mag stripes?
really easy to forge -- and someone found a way to monetise the New York Ciry system.
Metal disks --
People in NYC used to make a nice living selling metal slugs.
The Mifare system is "good enough" for a public transport ticketing system - just because there is some encryption involved it attracts hackers and publicity which tends to ignore the economics of issuing a couple of million travel passes worth a few dollers each.
Having said that the MBTA acted like complete dickheads, and, the lawyers who advised them should be sued for malpractice and incompetance. The students demonstrated good faith by contacting the MBTA, furthermore they intended to hold back some vital details of the hack from thier defcon presentation to give the MBTA some breathing room. All the students research and the results were placed into the public record as evidence in the case -- so now the complete hack is available to any script kiddy.