Just a small suggestion that I just thought of that might be beneficial to stores.
At the moment you can select 1 of 4 statuses for products listed in the shop however my proposal would be to add a 5th status - a "Pre-Order" status which would allow customers to buy a product with that status however also has a customisable field where site admins can enter an estimated date that the product will be back in stock.
And here is how I'm imagining my proposed "Pre-order" status would look like...
Public Facing View
Perhaps instead of a text field where site admins can enter that information, it could literally just be a date and the site just automatically adds the text part. Eg, if a product comes back in to stock on 20th March, I would just enter the date 20/03/2017 (DD/MM/YYYY) but the customers still see the "Product will be back in stock and ready to deliver on [DATE]" or something similar.
Customer support service by UserEcho