In case you haven't noticed walkers has changed a lot since the first season. At first, they were somewhat in good shape, and now it seems like they are decomposing. So if this theory is to be believed all zombies will die out and humans will repopulate the world without a threat of being infected. But here's the catch: This will most likely lead to a massive civil war between the remaining survivors. Now, this is the theory we actually believe in because not only will it give "The Walking Dead" an epic ending, but it will also be in line with the central idea that humans are far more bigger threat than Walkers will ever be.
Image Source: www.moviepilot.com
This theory states that the whole story of "The Walking Dead" is happening in Rick's mind while he is in a coma. And if it seems like too much for you, just wait because there is more. If this theory is to be believed, all the people Rick encountered throughout the series are hospital staff. So Hershell could be his doctor, Maggie, a nurse, and Father Gabriel, well, a priest. Crazy, right? But one thing is certain: this ending would make the fans angry. Luckily, Robert Kirkman, a creator of the series, already shut down this theory in a tweet, years ago.
Image Source: www.applauss.com
Given the fact that "The Walking Dead" is basically the story of Rick Grimes, it makes sense that the show will end with his death. And if we had to guess how will he die, Rick sacrificing himself to save Carl and Judith seems like a good way to finish his character arc and the story for that matter.
Image Source: www.nocookie.net
If the U.S. is the only country infected, then there's a high chance that European troops would come in the end to exterminate the remaining population including Rick and the group to stop the virus from spreading, and later they could repopulate the country. Although this theory might seem dark and cruel, "The Walking Dead" proved itself to be the show where even something as gruesome as can easily happen.
Image Source: www.nocookie.net