An interesting idea, as it would also alter the trajectory of a lot of families like Gates, Soros, Allen, Bloomberg, Murdoch, et al.
Ironically, I assume the descendants of Adolph Ochs (purchaser of the NYT), probably aren't hurting for money. Wikipedia says: "Of the two categories of stock, Class A and Class B, the former is publicly traded and the latter is held privately—largely (over 90% through The 1997 Trust) by the descendants of Adolph Ochs, who purchased The New York Times newspaper in 1896."
Seems a steep inheritance tax like this also penalize people such as professional athletes, some of whom can achieve generational wealth to ensure financial security for their kids, and their kids.
It'd also penalize people like some guy from a modest or poor background who in this day and age, invents a widget in his garage that nets him $200 million (not unlike Gates or Jobs). Would that be fair to heavily tax it just so he can't pass it on to his kids because his kids don't deserve it? If that sort of taxation was already in place, I suppose either there would be no Bill Gates Foundation (which a lot of people like), or else there would be a lot more offshore shell companies.