According to a recent internal leakage document, if you have a damaged iPhone 6 and are eligible to replace the entire device, then maybe Apple will replace you with an iPhone 6s Plus instead of fixing it.
Apple does not specify which products are an eligible replacement, nor give reasons to replace iPhone 6s Plus for the user but the cause may come from Apple is seriously short of the battery to replace the iPhone 6 Plus and Apple may have to return in April.
Also according to MacRumors Apple may have stopped producing the iPhone 6 Plus so it may not be possible to deliver a large amount of battery power for a short period of time. With some basic errors such as the display, battery, speaker, rear camera, or Taptic engine, Apple’s authorized dealers can repair and replace themselves with some special cases. The faulty Lightning port or faulty motherboard will force Apple to replace the whole device.
TechBlogUp will further inform you if this program is officially launched. Have fun!