Why does a customer ask a shop assistant "will you be getting any more in" instead of "will you get any more in"?
Why is future continuous used and not future simple?
In your example there is little difference in substantive meaning. However, use of the continuous implies repetition whereas the simple future is silent on that issue. Usually if a shop is going to stock an item, it will receive deliveries over time rather than as a singular event. Consequently, the continuous reflects the speaker’s recognition of normal practice.
Notice that the future continuous would not be used in the question below because now the focus is a singular event
When will you next get some in?