We've probably all had this happen at one point or another: you probably wanted to download an update for your smartphone ~1.6GB brick of an update file. On Android, normally this gets downloaded to the user storage partition and flashed to the system partition. But wait, if your phone is full of pictures, or videos, or apps, there may not be enough space to store the update file. In such circumstances, the update fails, and the user is told to "free up some space."
According to the latest source.android.com documentation, Google has cooked up a scheme to make sure that an "insufficient space" error will never stop an update again.
Starting with Android 8.0, the A/B system partition setup is being upgraded with a "streaming updates" feature. Update data will arrive from the Internet directly to the offline system partition, written block by block, in a ready-to-boot state. Instead of needing ~1.6GB of free space, Google will be bypassing user storage almost entirely, needing only ~100KB worth of free space for some metadata.
Streaming updates is a new feature built into Android 8.0, but, oddly, the docs say Google is also back porting the feature to Google Play Services. That will enable this feature on "Android 7.0 and later" devices with a dual system partition setup.
With this feature, you'll be able to download updates to your phone even when your phone storage is full!