Once you've outgrown a single physical server, you can continue to scale the Trench cluster by spinning up more Trench application servers and switching to dedicated Kafka and ClickHouse (either self-hosted or via cloud offerings). You can also shard Trench itself depending on the structure of your data (e.g. 1 Trench instance per customer, use case, etc.)

Auto-archiving to cloud for Kafka (Confluent, AWS KMS, etc.) / ClickHouse (ClickHouse Cloud, etc.) is definitely high on the roadmap.