Coincidence or not, the Nexus 4 was launched four year ago, which means it’s not supported by Google anymore. There are not major software updates that are supposed to hit Google’s previous flagship smartphone, but that doesn’t necessarily means the Nexus 4 is completely dead.
The Nexus 4 is great device, so it might could survive four years without an issue. This means that if you couldn’t afford to buy another phone to replace it, or simply didn’t want to, there was no reason to do it other than the fact that Google wouldn’t support it with software updates.
After Google announced Android 7.0 Nougat, the Nexus 4 wasn’t among compatible device, which wasn’t a surprise at all.
The search giant announced that it will offer regular software update to all Nexus/Pixel devices that are about 1 year and a half old.