I wouldn’t see it as a replacement.
SQLite and DuckDB solve different problems and actually complement each other quite well. SQLite is excellent for transactional workloads (OLTP), while DuckDB shines for analytical workloads (OLAP), especially time-series data and aggregations.
We’ve been using both side-by-side in an open-source project for about two years: SQLite for configuration and transactional data, DuckDB for historical sensor data and analytics. So far, it’s been a very good combination.