At Citus we're actually very excited about the parallelism improvements within Postgres. For us at Citus the core of what we do is allow you scale horizontally

At Citus we're actually very excited about the parallelism improvements within Postgres. For us at Citus the core of what we do is allow you scale horizontally beyond a single node. We view the parallelism work within Postgres as complementary, as we can focus on the distributed aspects while letting each node handle it's own workload. Some of our customers do today very much leverage the parallelism Citus brings, but again that's across multiple nodes. A number of our customers don't choose Citus at all for real-time analytics, instead they're more focused on a more standard OLTP application, often multi-tenant app, that they need to scale.