In combination with Google and various software applications you already have solutions were customers can receive next to real-time offers on a daily basis. The difference is that the customer has to opt in for this software that will then gather relevant offers.
You also today have the possibility to while searching via different codes Bar c, etc for a product to receive comparing offers in the vicinity of your location.
IoT might in the future offer improved combinations of these techniques. For example shelf sensors might record that there are only 5 items left on a particular shelf which would lead to an automatic refill order to the supplier and that the store would run a one-time promotion since these particular products on the shelves might cut it close regarding shelf life.
Important thing to consider is that IoT is 3 things:
You can improve traditional equipment (eg. retail equipment, scanners, cashier machines etc) by combining them through a central point in the store comparing them with a set of metrics that will allow retailers to act in real time in what is happening in the store
Retail shopping malls could improve in combining various techniques that can synchronize with the shoppers mobile phone.
IoT will allow future products to improve when it comes to relevant metrics that can be synced with the internet (warranty, "health checks", maintenance, optimizing operations etc.).
The "problem" with IoT in retailing is customer integrity and that the customer has to give up a lot of information. With mobile technology this is already up for debate on how much information is being leaked via our mobile phones. Regardless, I think that we are moving towards some kind of opt-in solution and that if the customer gives up a lot of information he/she will have to receive something for it in return to make it worth their while and in order to avoid information poisoning. Remember when your letterbox got filled with coupons that it became so much that people opted out for it again?
So sure, it will be possible to create improved retail systems with IoT, sensor (Rfid etc) and mobile technology that most likely will reward customers who frequently visit malls.