A huge number of people already barely use DNS. They go to places like "The Pirate Bay" by entering "The Pirate Bay" in the Google Search window, and following the first link or two that they find. So, if Google indexes 194.71.107.27 or there's a Wikipedia link to it (since, you know, that'd be newsworthy), the effect of a DNS ban has little impact on the original discovery of the site URL.
Some (stupid) ISP's already take care of this search mechanism... enter a bad URL, go right to a search page. Most browsers will also be more than happy to help out.
It'll break bookmarks, but once you know something exists, has value to you, and you know how to find it, it's nothing more than an inconvenience.
In other words, delisting doesn't work for longer than it takes a new URL to propagate.
Taking over the hostname would last a little longer, but news travels fast.