If you think about it, the only time you know when someone has placed an order and what they have ordered, is when you get a communication from the payment processor advising you of a sale.
With the forthcoming inventory control, if it works like it does in other carts, it will remove an item for sale when the stock level is less than one (zero). It usually does that by removing the add to cart button.
Some people will only have one item for sale, if it's an original piece of artwork etc so a re-order facility wouldn't be an option for them as when the item has gone its gone.. Others will simply be out of stock of an item and will be able to re-order to offer the item for sale again at some later stage (if their own suppliers are not out of stock). The only real workaround is to have something in your item description, saying that if they want to know when an item is back in stock to click here. Have that link send you an email with the item number as the subject.
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