Back in April, it was revealed that Google is working on a program called Android Silver, which is a premium support package including special assistance and services. Similar to the current Nexus program, devices that qualify for Android Silver must have essentially no customizations applied to the Android interface.
Around the time that Android Silver was revealed, rumors started to appear claiming that it would replace the current Nexus program. Instead of having OEMs create devices to be branded 'Nexus', they would instead produce top-end Android Silver devices with vanilla software experiences.
However, according to Dave Burke, the head of Android engineering and the Nexus program, the Nexus program is here to stay despite the impending launch of Android Silver.
"Android Silver is not something that we are commenting on right now. [...] People have been commenting about Nexus because there is something else and they think that means the end of Nexus. That is the totally wrong conclusion to make"
The next wave of Nexus devices will likely be launched in a few months from now, and rumors indicate it will potentially include a 9-inch tablet alongside a new smartphone (the Nexus 6). For now, Google is focusing on launching a selection of Android Wear devices that were recently detailed at I/O.