The owners released in 2014 the iPhone 6 Plus can absolutely free to get more new iPhone 6S Plus.
This became known from the leaked document sent out by Apple authorized service centers. It is worth noting that such a “gift” to receive, not all users. To do this you must meet certain requirements.
Free replacement for iPhone 6 Plus iPhone 6 Plus is only possible until March of this year. The document does not specify who exactly can obtain a new gadget. Likely replacement will be made if the device is not serviceable or the service center will not have the required components. Since iPhone 6 Plus has long been out of production, and spare parts for it already ceased to be issued.
If you are lucky, along with the iPhone 6S Plus you will get a more powerful processor, display with 3D Touch support, improved camera, more RAM and an extra year of iOS support.
Note that this is not the first such case. Last year, Apple similarly changed iPad 4 iPad Air 2.