The notion that Apple will release an "iPhone 6c/7c" gained steam this week after China Mobile included an iPhone release during a corporate presentation. Spotted by Chinese site Mobile 163 (via AppleInsider > Gadgetz Arena), China Mobile said it would release an "iPhone 7c" in April.
Image from Mobile 163 of China Mobile Presentation
According to Mobile 163, the text blocked in red indicates that Apple will be releasing a new device in April, and the device would be "iPhone 7c." The site speculated it would be priced at 3,200 Yuan, or $493 as of this writing.
Aside from the name "7c," this event dovetails with other rumors that Apple will be releasing a new 4-inch iPhone model in March or April. Few in the West expect Apple to release an entry-level model with a "7" moniker when its flagships are iPhone 6s and iPhone 6s Plus. Instead, most observers thing Apple would release an iPhone 6c.
Apple itself has made no such announcements, and the company isn't known for giving advanced notice to its carrier partners. Plus, this report is something like fourth-hand across language barriers.
The leaks that end up being accurate are usually those with a large number of sources. This particular story hasn't yet crossed that hard-to-quantify threshold that makes if feel solid, but signs are certainly headed in that direction.