It was when the shuttle bus stopped coming that Luka Fernandes began to worry. Fernandes was a student at Newbury College near Boston, whose enrollment had declined in the previous two decades from more than 5,300 to about 600.The private, nonprofit school had been placed on probation by its accreditors because of its shaky finances.After students went home for their winter holiday, an email came: Newbury would shut down at the end of the next semester.