Years ago I found out how close Katie Holmes came to being cast as Buffy in the TV version of “Buffy the Vampire Slayer” (and I still always try to envision her singing in the magical “Once More, with Feeling” episode). But the rest of these what-might-have-been casting decisions leave me breathless! Imagine Isaiah Washington as McDreamy in “Grey’s Anatomy”, Ryan Reynolds as “Xander” on “Buffy”, Sandra Bernhard as “Miranda” on “Sex and the City”, Whitney Houston (R.I.P.) as “Sondra” on “The Cosby Show”, or Ashlee Simpson as “Elena” on “The Vampire Diaries”!!!! E! Entertainment’s “TV Scoop” list of “Amazing TV Roles That Almost Went To Other Actors” just goes to show you how vital the right cast and casting outcomes are to a production.