Nexus devices are made by a single manufacturer every year. Nexus One was manufactured by HTC in 2010. Then the 2nd Nexus was Nexus S, which was made by the Samsung, the biggest smartphone manufacturer today. 3rd Nexus was the Samsung Galaxy Nexus, which was again made by Samsung. Next 2 Nexus devices, the Nexus 4 and 5 were made by LG and Nexus 6 was made by Motorola. Then the latest Nexus 6P and 5X are made by Huawei and LG respectively.
There were some rumors that HTC will make the next Nexus devices and the rumors come to be true. Although HTC is struggling in Android market and its phones are not a big success anymore. So it looks like HTC has decided to adopt another business approach by making the Nexus devices for Google. The deal has been made for 3 years, which means that HTC will make the Android N powered Nexus devices this year as well as Android devices for the next 2 major versions of Google Android.
It was also rumored that HTC will at least make 2 Nexus devices this year. A 5-inch device and a 5.5-inch device. So after one rumor got true, there are more chances that HTC will actually make these two devices.