For what it's worth, MotherDuck and DuckLake will play together very nicely. You will be able to have your MotherDuck data stored in DuckLake, improving scalability, concurrency, and consistency while also giving access to the underlying data to third-party tools. We've been working on this for the last couple of months, and will share more soon.
i think a way to see it is MotherDuck is a service to just throw your data at at they will sort it (using duckdb underneath) and you can use DuckDB to iterface with your data. But if you want to be more "lakehouse" or maybe down the line there are more integrations with DuckLake ir you want data to be stored in a blob storage, you can use DuckLake with MotherDuck as the metadata store.