Evolutionary paths that appear possible by combining this work and the analysis of Garufi et al. (2017). The dichotomy in inner disk cavities is shown at the center: high-NIR cavities have a residual inner dust component, possibly a belt/warp, that shields UV radiation and enables CO (vibrationally cold) to survive into the cavity; low-NIR cavities are instead dust- and gas-depleted, and CO (here vibrationally hot) is detected only close to the cavity wall.