That's only a problem for Disney. The rest of the world gets to benefit from an explosion of creativity, and more available content.
I definitely support a short copyright period (say 10-20 years). Beyond that, as the original creators of the characters, any further 'official' content/stories created by them are likely to be popular if they are any good (and would be subject to their own copyright period). But if someone else takes on those characters and manages to produce great stories with them. Well fantastic, let's allow them to, and reward them for it.
I definitely support a short copyright period (say 10-20 years). Beyond that, as the original creators of the characters, any further 'official' content/stories created by them are likely to be popular if they are any good (and would be subject to their own copyright period). But if someone else takes on those characters and manages to produce great stories with them. Well fantastic, let's allow them to, and reward them for it.