The Nexus 6 is widely expected to be based on the LG G3, a smartphone that LG will officially unveil on May 27th. We have no further details about the Nexus 6 from this leak, but we do expect to hear more about it by the time of Google I/O on June 25-26th. We ought to clarify, though, that traditionally, Google launches Nexus phones in the fall.
The Nexus 8 is clearly a tablet, and most recent findings in the Chromium Issue Tracker hint at a Google-HTC collaboration for it. Its rumored release date is this summer, when it could launch along with a new Android 4.5 version.
Interestingly, these two might be the last Nexus devices to come out of Google. Reports have surfaced about Android Silver, a program promoting timely updates and pure Android versions on multiple devices, that is said to replace the current Nexus initiative.