I sincerely doubt that the children of tomorrow will grow up without personal computers just because the iPad is around. Computers are dirt cheap, can do way more stuff, and kids aren't afraid of them like "mom" is.
It's difficult to say whether the iPad will be a net win or loss for software freedom, in the long run. Never have so many developers been so tightly controlled by a single vendor. However, the iPhone/iPad platform has opened up a world of opportunities for developers, inspired the creation of other, more open app stores, and will probably encourage, far more than deter, aspiring young developers, as Gruber's anecdote illustrates.