I have two schools of thought.... Ghost kitchens are are great idea once the nuances are resolved.  A Ghost kitchen also stimulates a customer base interested in ordering out verse cooking; with that being said customers are not necessarily loyal to one place to eat which gives brick and mortar  establishment  an opportunity to capitalize even more on their take out business.   As far as taking business away from walk in Restaurant's I doubt that Ghost kitchen will have much of a negative impact because when dinners go out to eat, it mainly about the food but the experience is just as important.  People go out and dine for the atmosphere,  relaxing and enjoy a good meal, something delivery can not offer.