In a way its kind of immaterial if there is a "run" on a credit union. I can't imagine very many members have shares over the insured limits (250k in checking, 250k in savings), so the deposits have to be almost entirely insured. Also all the little old widows whose GM pension gets deposited every month are not gonna organize and pull their money like silicon valley VCs. They could still be insolvent and get federalized or whatever, but the damage to real people should be minimal even in this kind of unlikely scenario.