Often when there is a coaching change, some incoming recruits ask to be released from their LOI. It's up to the school's discretion if they grant that request or not. If a player is released, they can go elsewhere and be eligible immediately. If they are not released they can transfer, but would have to sit out a year (unless the NCAA approved a waiver for immediate eligibility). Usually a request to be released from a LOI is granted, because who needs a player hanging around for a year that doesn't want to be there?