I've recently learnt about ["NewSQL"](https://en.wikipedia.org/wiki/NewSQL) databases like: 

* Google Cloud Spanner (proprietary)
* Microsoft Azure Cosmos DB (proprietary)
* CockroachDB (open source)
	+ also see [How does CockroachDB compare to MySQL or PostgreSQL?](https://www.cockroachlabs.com/docs/stable/frequently-asked-questions.html#how-does-cockroachdb-compare-to-mysql-or-postgresql)
	+ also see [How does CockroachDB compare to Cassandra, HBase, MongoDB, or Riak?](https://www.cockroachlabs.com/docs/stable/frequently-asked-questions.html#how-does-cockroachdb-compare-to-mysql-or-postgresql)
* VoltDB (open source)

I was reading about them and learnt that they provide best of both worlds, that is NoSQL and SQL and are [ACID](https://en.wikipedia.org/wiki/ACID) compliant. 

CockroachDB for instance provides some compatibility with PostgreSQL and I can use PostgreSQL clients to use it just like that.

I was struggling a lot recently what should I choose for my next project and I would like to build it with scalability in mind(which is definitely harder when using MySQL etc.), and because I like what NoSQL and SQL databases provide, does it mean NewSQL databases are **silver bullets?**