system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel] So if Secret Wars is supposed to take place in 2015 (sliding timescale means Marvel is always in the present), and that's gonna result in an All-New Marvel universe, how can 2099 exist?
gpt
Marvel has a many-worlds concept of time with one primary self healing timeline. 

What that means is there is one main timeline that is full of chronal energy and points in one direction- towards the future. Every action causes an infinity of parallel timelines to emerge, most of which are reabsorbed back into the primary timeline because they don't have enough difference to break away.

This allows for single events to change the past in a way that causes paradoxes, but the future timeline will immediately attempt to heal it by removing the offending portion of the timeline. For example, if cyclops from the past shows up in the future and future Cyclops kills him, the timeline will attempt to resolve that problem by removing future Cyclops. Obviously his loss at that moment wouldn't have changed the future enough to cause a chronal fracture.

But some changes are so critical to the orderly continuation of the timeline that when they happen they fracture it- causing a parallel timeline of the current universe- separate reality that exists on it's own.

2099 is one of those universes. Something happens between now and 2099 that made that universe possible. No matter what happens here, that event happens, and when it does the split occurs. It may have happened a hundred years ago, it may happen in ten minutes. Only people who analyze and catalog chronal energy or have cosmic awareness can ever truly know.