The great thing about My Hero Academia is that it's not just a superhero-themed anime/manga that's great a world building and character development - it's also great at mystery. Since My Hero Academia began, series creator Kohei Horikoshi has been dropping very purposeful breadcrumbs about the mythology behind the two big powers representing good and evil: One For All and All For One (respectively). However, the latest chapter of My Hero Academia revealed some major twists with the power of All For One, and in doing so, the series may have also revealed the master plan that series big bad All For One has been hatching, all along.
Warning - My Hero Academia manga chapter 270 SPOILERS Follow!
This pivotal chapter of My Hero Academia sees One For All's disciple Dr. Ujiko / Garaki finally reveal some key details about his history with All For One. We learn that All For One passed his power on to his successor Tomura Shigaraki some time ago, and has been using a copy of his quirk developed by Garaki as a replacement.
With the reveal that Tomura Shigaraki has not only had his disintegration quirk boosted by Ujiko, but also has the power of All For One at his disposal, says quite a lot about All For One the villain's true intentions. It seems that All For One learned from the example of his brother and the passed-down progression of the One For All quirk. He also did a lot to mold Shigaraki both mentally and physically (through his quirk) to become what's potentially the most powerful version of All For One the world has seen. Shigaraki is already a villain mastermind and quirk powerhouse, who has shed virtually any semblance of good or intimate personal connections from his old life. He is All For One's ultimate weapon.
But what's the goal of that ultimate weapon? My Hero Academia chapter 270 may also foreshadow that, as well. Dr. Garaki is finally confirmed to be the originator of the Quirk Singularity Theory, which predicts that quirks will evolve over time to the point of spiraling out of control and destroying society and/or the world. And now, it's looking more and more likely that the singularity could be exactly what All For One is hoping to achieve.
With Deku quickly becoming the strongest user of One For All, and Shigraki matching him with an evolved All For One power, My Hero Academia's big bad may be just the type to watch the world burn - and gladly provide the match.