We're working on suitable replacements for these services. In some cases, e.g., Cloud Tasks, we're pretty close. Others will take a little longer. We'll share updates as we make more of these services available.
Also I did find that someone wrote a ndb-like wrapper around the cloud datastore API.
https://github.com/Bogdanp/anom-py
I haven't tried it out yet.
Although i think any reasonable path to upgrading to 3.7 might need atleast some wrapper like that around the datastore(even if it's not 100% compatible), otherwise forcing people relying on that to re-write the entire data layer. At this point i might just start re-writing the app, to move to something with less lock-in like Mongodb. But i'd love to hear what other people's plans are for this.
"The ndb ORM library is not available for Python 3. You can access Cloud Datastore through the Cloud Datastore API. You can use the Google Cloud client libraries to store and retrieve data from Cloud Datastore."