Update: We have published a paper on this discussion, including updates from interviews we conducted, at ICSE-SEIP 2020. Having spent over a decade researching configurable systems and software product lines, the phenomenon of feature flags is interesting but also deeply familiar. After reading papers and blogs, watching talks, and interviewing several developers, we see some nuance but also many issues that we had thought were solved long ago. Several research communities have looked into featu...