Roughly 5 million people are admitted to University every year in the US[2]! So maybe 0.08% of all University students get a free ride at an ivy league. Really this makes no difference except for padding the Ivy League's statistics, its of little to no help for most 'talented low income' highschool students.
[1]http://theivycoach.com/ivy-league-admissions-statistics/
[2]http://nces.ed.gov/fastfacts/display.asp?id=98
Edit: To address most of the responses below. I'm implying that even if all appropriate students applied for these programs, as the article suggests, it wouldn't make a difference because some tiny fraction of them would be admitted. There are very few opportunities for low income students unless they are willing to take on the burden of debt. Some lottery that gives a tiny fraction of them free tuition is not a solution, it is offensive to suggest they have opportunities they simply do not have. Fix the broken system, correct tuition costs!