A lazy shopkeeper has to type in the price of carton of ice cream into the cash register. After he’s finally done that, the customer has to wait for her change for nearly two minutes. Then he puts the ice cream very slowly in a plastic carrier bag.
Another customer who has been watching all of this suddenly says: ‘Hey, girl, I think your ice cream will have melted before you leave the shop.’
The girl says: ‘Yes, I think so too.’
Are the underlined sentence grammatically correct? If you find a more natural dialogue, please share it with me.
I can’t say anything about the first sentence but for the second I think that “Hey, girl, I think your ice cream will melt before you leave the shop.” will be better. Just the all thing with ‘’ will have melted’’ is like the ice cream is going to be melted before, but the use of the tense is wrong. I think that for this sentence you only need to use a simple future tense, not present perfect tense.