According to etnews.com (translated), the iPhone 7 might come exclusively with an A10 TSMC chip. The A9 chip was produced by both Samsung and TSMC. However benchmarks proved that the A9 chip supplied by TSMC performed better and the iPhones battery lasted longer. Also these chips ran cooler than the ones Samsung provided.
Considering the above facts and past experience, Apple has enough time until September to choose a good provider and frankly TSMC has the better chance. As other speculations, this is just a rumor, until we see an actual iPhone 7 device.