Oh come on, the two years was the term of each individually approved illegal's work permit and deportation deferment. It was not the end date of the DACA PROGRAM! The program, which included the opportunity for renewals, had not expiration date.
The only mention of 60 days in the memorandum is the time-frame ICE had to prepare and enact the program requirements into their mission and the time USCIS had, from the date of the memo, to implement the program. There was nothing in the memo about more details coming out in 60 days. The Napalitano memorandum was an executive action that established the program (Secretary of DHS can't make law).