Yep, newly created formations on Citus Cloud will be PG10 and the latest version of Citus. For any existing customers on PG 9.6 and older versions of Citus we'll be upgrading those that opt in. Our upgrade process leverages our underlying disaster recovery and high availability infrastructure[1] so we can generally upgrade an entire cluster regardless of data size in under a couple of minutes.
[1] https://www.citusdata.com/blog/2017/03/23/a-look-into-disast...