I don't really think illegal content will be an issue, at least for the file hosters. The files are split up and heavily encrypted. If in the distant future, somebody would decrypt alle the data you are storing, they probably wouldn't even have a visible portion of an illegaly stored image, without aquireing all the other parts first.
There will always be people who abuse such systems, but should it prevent us from a more comfortable, independent, exciting future?
I don't think so.