I was specific in my first statement as to which region I was talking about. ;-)
I guess it's different for each retailer.
I work for a decent sized one in the US (Fortune 500). The stores aren't big (so there's only about 5 pin pads per store), but the store count is about 5,000 (with a new location being opened on average every business day). So that's 25,000 pin pads in the field, none of which are NFC enabled.
Like all hardware, these things have an expected shelf life, after which they get refreshed. But in our company, that refresh is based on the date the store was installed. So when the pin pads hit their shelf life, it'll be a slow rolling process to replace them all. At lease a decade until the entire chain has been refreshed.
Software's a completely different story. Like most major retailers, we bought ours off-the-shelf, along with the rights to customize the code. We have an IT department of about 200, including an internal app dev team that does nothing but modify the POS code to add new functionality requested by the various parts of the company. The ability for customers to pick up orders at the store, yet another pre-paid service that has to be activated at the time of purchase, the ever changing changing the requirements on how electronic tenders can be handled when the network is down, etc, etc. This team pushes out several new updates a year, and the cost of this team falls under "business as usual". They coding an update that pulls a QR code from a scanner pointed at an iOS device would be one of the easier updates they've done recently. It takes a few weeks to get these updates through the QA team, and deployed to the entire field.
I can see our marketing folks getting excited about Passbook. Passbook is done through an iOS app, which means a specific customer that they can market to. Send them targeted coupons via the app to bring them back into the store more often. Load an extra $5 on their gift card if they buy certain items that a particular store is overstocked on. There seems to be a lot of opportunities for creative retailers.
Where's the opportunity to build sales via NFC? As a retailer, you don't seem to get anything more out of it than if a customer swiped a card.