At Google's IO developer conference that was held on the 17th May, Google unveiled the Android Go, an initiative created in order to fill the void left by the Android One program, which hasn't resulted in a new phone in a long while.
However, Google isn't calling this Android One 2.0, so there will be quite a few differences between Android One and Android Go. According to Google, we where inspired a lot by the YouTube Go app when developing Android Go. Every single device launching with Android O and later OS versions having a 1GB of RAM or less will get Android in the Go configuration.
The Go Configuration is basically the operating system is tuned to work with lesser hardware as well as very limited network connectivity and small data plans. You will get data management in Quick Settings, and an API will be made available to carriers to tap into this. So you'll always know exactly how much data you've still got in your plan.
Another cool thing about the Android One is that you'll be able to quickly top-up your data allotment inside Android's Settings - without the need to call your carrier or visit a store. The Data Saver feature will be on by default in the Android Go configuration, and Google promises it will "Go-ify" all of its preinstalled apps, building upon the lessons it's learned from the rollout of YouTube Go.
If you are a third party app developer and want to get your showcased inside the Play Store of the owners of Go devices, then you have to adhere to a Google Best Practices document called Building for Billions. This basically means that they should take into account things such as limited network connectivity (and small data plans), as well as low use of hardware resources, when building your apps.
Also, according to Google "the first Android Go devices are going to arrive in 2018".