HTC is no stranger to the Nexus line of devices from Google. In fact, they were the first partners, to bring a Nexus phone, when they released the Nexus One, an improvement on the existing HTC Desire back in the day when the Nexus line was launched. However, since then, HTC has just worked with Google on the most recent Nexus tablet, called the Nexus 9 and absolutely no other smartphone. The likes of Motorola, LG, Samsung and Huawei have all produced Nexus phones while HTC has concentrated on its Desire and One line of phones.
Allegedly related to HTC Nexus devices codenames are: T50 T55
— LlabTooFeR (@LlabTooFeR) January 19, 2016
However, it looks like HTC and Google are set to partner once again, for the next two Nexus phones. The news also indicates that Google will continue with the approach to bring two Nexus phones this year, just like this year with Nexus 5X and Nexus 6P. The two devices that HCT is working on, are codenamed T50 and T55, though there is absolutely no news about these and what these phones will come with.
We assume, that one of the Nexus phones will be an improvement on a device in the HTC One series, while the other one would be from the Desire series of phones and come in more plastic or low-cost build. Now that the cat is out of the bag, dont be surprised, if in a few days the first set of images start to leak out, but for now, just know that there would be a Nexus made by HTC this year.