The Verge says:

Following a rough fourth quarter that saw shrinking Nook sales, Barnes & Noble has revealed that it plans to close up to 20 stores a year over the next decade, The Wall Street Journal reports. The plan would cull up to a third of the bookseller's retail stores, which Barnes & Noble executive Mitchell Klipper says will bring the total down to 450 to 500 stores — the WSJ notes that the chain currently has about 689 retail stores in operation.

B&N responded to the WSJ report by saying that they always close between ten to twenty stores a year, which is perhaps not very comforting, considering they're not opening stores at anywhere near the rate they used to.