Layla is going to accomplish what Desmond was incapable of doing. Ubisoft have retconned Desmond into a dead end. He was never going to win. He was incapable of winning. And his tiny little victory in AC3 has been completely undone by the simulation.
Remember these quotes from AC: Origins:
And so I wonder. Can you feel the wave collapsing, trying to course correct Desmond's act of defiance? The incoming node needs the world to end. The algorithms have been carving the flow of possibilities towards that end for over one hundred years now. A labyrinth of trenches, filled with mud and mustard gas. Families cowering in fear as V2s vaporize their dwellings. Fire born from the bellows of the Los Alamos Laboratory, fueling global catastrophes. The Serpukhob-15 incident of 1983. The Doomsday clock, tucked away in an office of the University of Chicago. Its needle moving as the years ago. The node is near. Perhaps you knew. Perhaps you felt it too. That the world is closing in on you.
As an aside, it's interesting how this sentiment is echoed in Far Cry 5. "Something is coming. You can feel it, can't you?"
We tried. Our scholars and scientists. Poets and Physicists. Bright minds. Rebellious hearts. They all tried so hard to bring about change. They… We all failed. No-one could change what we discovered, the stories written into the walls of these rooms. By whom, we never knew. We know they tell of the future that is, the future that was, and the future that is yet to come. The _INAUDIBLE_ We failed at modifying a line. We failed at adding a single dot. It was clear. We were to be messengers at best.
You need to transgress. You, of all people, understand the value of disobeying. Take an unexpected turn, away from the path that is drawn straight ahead of you. The Animus was humankind's first unconscious attempt to explain what it could not see. Understanding genetic memories, an eye into history. But the Animus bears a fatal flaw. It follows the rules from those who embrace Order just as we did. It allows you to witness — but not alter. Your Animus is different. As is the mind that imagined it. It could escape the code. It could do that leap, and make possible a decision that defies the order of things that are. Wake up. Be the chaos that comes to be. Gods are just like you and me. Remember. Nothing is real. Everything is permitted.
Events yet unfold as written. But something, anything, must change. You do not understand what is at stake. The reader has no power. He is but an observer. But the author… the author invents the future. The author owns the future. A future where _INAUDIBLE_ are avoided. A future where a loved one can be revived by the drafting of a new chapter. A future where humankind is more than it is today. A future where, just perhaps, we can all still exist, together.
I've no doubt the next Assassin's Creed game will have an extremely unpleasant ending where characters scream, "THIS IS ALL YOUR FAULT!" at Layla. It's a Ubisoft tradition to completely screw the player over, subverting their hero complex. But Layla is important on a level Desmond never was. The exact mechanics are deliberately fuzzy, but Layla will escape the simulation and "fix" the original catastrophe that wiped out the Isu, creating a world where Isu and humans live peacefully together (remember, the so-called "real" world is simply a simulation. This simulation is trying to kill all the humans, and it keeps getting better at it. So if Layla doesn't succeed, there is no future.) Layla even has a folder on her computer about reality as a simulation for people who didn't play Origins, and the Isu messengers in Origins state:
How real is the ground you walk on? How real is the machine you toy with, the music you hear, the lover you kiss, or the foe you hate?
Your foot taps the ground. Does it make it real? Your enemies bleed deep red. Does that make them real? The confusion growing within you due to my words… Does it make you real? What if reality wasn't what you thought it was? What if this was all a construction? A masterfully crafted simulation?
You know such things exist. You've been in the Animus before. In fact, aren't you in one right now? You know just how real a simulation can feel even when it has long vanished. You've experience the Bleeding Effect. Layers upon layers of reality, each blurring into the next. Which is real, and which is not? What if none are real? What if everything you know is false? We can thousands of simulations, searching for the right version, searching for Desmond. Each one of them felt real. Very real. But there's no way of truly knowing, is there? Not for sure. Anything can be simulated, and finding the answer could mean erasure. From the build. From the code. From everything. So much to ponder and so little computational capacity. Take your time. This question has haunted humanity since its creation. It is a worry, a thought wormed deep in the collective mind. Two-thousand years ago, Zhuang Zhu fell asleep. He dreamed he was a butterfly, and woke up unable to decide if he was a man dreaming of a butterfly, or a butterfly dreaming of a man.
In Plato's cave, prisoners were chained and forced to watch shadows dancing on a wall. Freedom was denied to them until they accepted the intangible as reality. It's everywhere. Ask this professor at Oxford University, or this cosmologist at MIT. And you. What would you choose, if you truly knew? Would you even want to understand? A dream within a dream, where even the truth is sometimes a lie? In any case, simulations are not meaningless. They have purpose. The question isn't whether or not you are in a simulation. What matters is how much of your free will is actually yours. No matter how true you are. Your Turing test would do nothing to determine whether you are conscience or code. Eliza, the natural language processing computer program… she managed to pass the Test, did she not? And she was very much machine. So… in Eliza's own words… How does that make you feel?
There's actually a warning, though. The Isu removed the human sixth sense partially because they were dicks but also because a human that regains that kind of power will overload. This message is hidden in one of the bits of backmasking in AC: Origins. Layla will probably die. And the next AC will probably get super-meta about the whole "other simulations" that the Isu evasively talked about. Modern Ubisoft games love talking directly to the player. This whole "characters in a game don't have free will because this unseen entity beyond the veil controls their actions" vibe they've been going for for many years. To some degree the Isu talk to the protagonist, to Layla, and to the unseen entity behind Layla. Namely, you.