During the three decades since the invention of the first variability modeling approach (Kang et al., 1990), there have been multiple attempts to introduce advanced variability modeling capabilities. More recently, we have seen increased attention on textual variability modeling languages. In this paper, we summarize the main capabilities of state of the art textual variability modeling languages, based on (Eichelberger and Schmid, 2015), including updates regarding more recent work. Based on this integrated characterization, we provide a discussion of additional concerns, opportunities and challenges that are relevant for designing future (textual) variability modeling languages. The paper also summarizes relevant contributions by the authors as input to further discussions on future (textual) variability modeling languages.