A lot changes. There really is no way for someone to predict value on this sort of thing. For all we know, apple could go bankrupt in a few years and in 20 years no one will have heard of them. Then only people that buy them are for nostalgia, which means demand won't be high, so price won't be high.
Apple collectibles are only worth something because Apple is famous now. Imagine you had a 1980 compaq computer poster. Sure, its vintage and collectible, but you'd be hardpressed to find someone willing to pay $30 for it.