“…Despite the growth of research on heritage languages (HLs) over the past three decades, we, as a field, have yet to sufficiently account for the grammar of the final generation of speakers of heritage languages, also known as moribund heritage languages. While numerous empirical studies have shown demonstrable changes in HL grammars across the lifespan (Benmamoun, Polinsky, & Montrul, ; Boas, ; Montrul, , ; Polinsky, , ; Putnam, Kupisch, & Pascual y Cabo, ; Roesch, ), similar empirical studies show robust maintenance of grammatical structures characteristic of preimmigration varieties in the final generation of HL speakers (e.g., Bousquette, ; Hopp & Putnam, ; Keel, ; Page & Putnam, ; Sewell, ). Still another branch of recent literature shows a third path, where HLs exhibit changes resulting in innovative grammars that are divergent from preimmigration varieties, but nevertheless maintain economical complexity and communicative functionality (Bayram, Pascual y Cabo, & Rothman, ; Łyskawa & Nagy, ; Putnam & Sánchez, ; Yager et al., ).…”