I'll just mention that I know quite a number of people (myself included) who have been admitted to and completed degrees at competitive four-year institutions, without high school diplomas. That being said, we're planning to transition ours into full-time university with community college coursework first, as a way of both maintaining challenge in strength areas and demonstrating college readiness without requiring a diploma.
Of course, I also don't believe that attending a flagship state university instead of an elite private will necessarily be shortchanging their educations.
