Delays, delays, delays.
Apple is expected to release the loaded with new technology iPhone 8. Although before that they are expected to launch the iPhone 7s and 7s plus in September. Rumours from a reliable source say that they are experiencing delays to not only the iPhone 8, but to all their models that are set to release in the near future. Compared to production cycles of the last few years, Apple are 2 months behind with regards to the iPhone 7 upgrades.
These are all unconfirmed rumours sent through by reliable sources; so there is a chance Apple might pull through and stick to their schedule.