Going concern value is the amount that a potential acquiree is worth to a buyer under the assumption that the business will continue in operation for the foreseeable future. The assumption of continuing operations is critical, for it implies that the business will continue to have a base of customers that will continue to buy from it, employees who will continue to work there, licenses and permits that will continue to be in effect, and so forth. Without the assumption of continuing operations, a business is essentially only worth its breakup value and the value of any remaining intellectual property. However, with the going concern assumption, an acquirer may be willing to pay much more for a business than the book value of its assets might imply.
In short, going concern value is the ability of a business to continue to generate positive cash flows in the future.