Abstract : By analogy with software product reuse, the ability to reuse (meta)models and model transformations is key to achieve better quality and productivity. To this end, various op-portunistic reuse techniques have been developed, such as higher-order transformations, metamodel adaptation, and model types. However, in contrast to software product development that has moved to systematic reuse by adopting (model-driven) software product lines, we are not quite there yet for modelling languages, missing economies of scope and automation opportunities. Our vision is to transpose the product line paradigm at the metamodel level, where reusable assets are formed by metamodel and transformation fragments and " products " are reusable language building blocks (model types). We introduce featured model types to concisely model variability amongst metamodelling elements, enabling configuration, automated analysis, and derivation of tailored model types.