"언제까지 그 신발을 판매할 것입니까?"
Translation:How long are you going to sell the shoes?
"until when, those shoes on sale for, is" would be an even more literal translation I think.
Is this like "How long will these be available to buy?" kind of thing? I was confused for a while.
"How long will the shoes be for sale" is better. The current one seems weird. "going to sell" seems like something that happens in an instance and then it's over. Not over a period of time.