This is, I imagine, true. However, it's also complicated. I'm sure that what the Zapp guys are thinking is that NFC is much easier and more appealing for customers than QR codes, so the Zapp app will be indifferent: if the POS has an NFC interface then the customer can tap, if not they can scan (or use Bluetooth or whatever). The Samsung owners can smugly tap and go, the Apple owners can pfaff about scanning. Again, though, not that simple. The NFC interfaces on the existing terminals are used for EMV (ie, NFC card emulation mode), which is why they will need upgrading to do cool stuff with Zapp (hence the appeal to acquirers).
