It takes decades, though. When did you last hear anyone seriously advocate a flat earth? How many Republican presidential candidates would raise their hands if asked if they believed the earth was flat? Sure, you can find a few far out fringe cranks who babble about it, just as there are a few geocentrists around, but it's a dead idea — not even Ken Ham pushes it, although I am wondering, since the Bible does support it literally, whether he doesn't secretly suspect the astronomers have been lying to him for all these years.
But there used to be more noisy flat-earthers around. A complete copy of a map by Orlando Ferguson from 1893 showing his flat earth model has been found, and it's gorgeous and hilarious. Here's his Biblical interpretation of the shape of the earth:
Spectacular! Unfortunately, the book that justifies this is lost, and all we have left for support are the notes on the map: Four Hundred Passages in the Bible that Condemn the Globe Theory, or the Flying Earth, and None Sustain It. This Map is the Bible Map of the World." Just like creationists, though, he does emphasize negative evidence: he ridicules physicists with their absurd proposition that the earth is zooming through space.
Let's hope that a century from now people will look back on the quaint artifacts from the age of Creationism and Intelligent Design as amusing curios that only a lunatic would find plausible.