A number of packages require Microsoft corefonts (Arial, Times New Roman, Courier New) or the free substitutes croscorefonts or liberation-fonts. Currently, many of these packages hard depend on media-fonts/liberation-fonts or media-fonts/corefonts when actually they would work with any of the three packages. I propose to add a new USE flag "corefonts" to virtual/ttf-fonts which ensures that one of the corefonts packages is installed. Other packages could then depend on virtual/ttf-fonts[corefonts] instead of individual packages. IUSE="corefonts" RDEPEND="|| ( media-fonts/liberation-fonts media-fonts/croscorefonts media-fonts/corefonts !corefonts? ( || ( media-fonts/source-pro media-fonts/dejavu media-fonts/droid media-fonts/freefont ) ) )"
If there are no objections until then, I plan to apply this change on 2018-08-14.