It looks like Google has finally decided to retire the Nexus 7 (at least for now). They pulled the device from the Play Store, and only the Nexus 9 is available. While you can still find the tablet in inventory at other retailers, that is just going to be back stock. Unless Google plans to create an all new Nexus 7 in the future, it looks like it will be put to rest.
It's a shame to see it go, because the 7-inch form factor is just perfect for some folks, but there are still very capable Android tablets at that size available. The NVIDIA Shield is a prime example with internal specs which are actually superior to the Nexus 7 (although at a higher price).
Source: Google Play Store