According to DigiKey, these have a Last Time Buy date of 1/15/2020. I imagine there'll still be old stock kicking around after that, but they will no longer be manufactured. Might be time to stock up. But we so seldom need them. Unless all our mice are about to wear out because they've reached that age.
DigiKey has 0 stock, but Mouser has them on hand, for those of us in the Americas.