We started by building some new functionality with Elixir. For example, a new read-only GraphQL API. Later, we might begin performing mutations and writes, serving all HTTP requests with Phoenix, and handling asynchronous jobs.

Although Elixir solves some of our problems, we don't want to rewrite things for the sake of rewriting them. That's why will probably keep things which work fine in terms of maintainability, scalability, etc. for now to move fast and learn more about the system and the domain (to avoid rewriting wrong features or right features rebuilt wrong).