The article investigates how ongoing grammatical change, widely documented in various native varieties, is adopted in advanced lingua franca use of English (ELF). It incorporates a broader perspective on ELF than previously, seeing it as one stage in the long diachronic continuum of Englishes rather than as an entity emerging in spoken interaction. The first part details a corpus project that produces written multi-genre corpora suitable for real-time studies of how ongoing variability is reflected in lingua franca use. It is followed with a case study investigating quantitative patterns in a set of core and emergent modal auxiliaries. The results suggest that in cases of substantial recent changes in the core varieties of English, lingua franca uses polarize the diffusion of change. The conclusions suggest that a diachronically-informed angle to lingua franca use offers a new vantage point not only to ELF but also to ongoing grammatical variability.