Language workbenches (LWBs) are tools to define software languages together with tailored Integrated Development Environments for them. A comprehensive review of language workbenches by Erdweg et al. (Comput. Lang. Syst. Struct. 44, 2015) presented a feature model of functionality of LWBs from the point of view of “languages that can be defined with a LWB, and not the definition mechanism of the LWB itself”. This vision paper discusses possible functionality of LWBs with regard to language definition mechanisms. We have identified five groups of such functionality, related to: metadefinitions, metamodifications, metaprocess, LWB itself, and programs written in languages defined in a LWB. We design one of the features (“ability to define dependencies between language concerns”) based on our vision.