Looks quite interesting for small setups, curious to read more about the limitations (E.g. " Added sqlite3 as the default storage mechanism. etcd3 is still available, but not the default. " - what availability promises can this make?)
In terms of etcd3 vs sqlite3, it is as reliable as most airplane systems that depend on it. https://www.sqlite.org/famous.html I think the "high availability by redundancy" story is oversold.
https://godoc.org/github.com/etcd-io/etcd/embed
This is something the Kubernetes community might consider as well.