^That is what I have been thinking about, and has me wondering, if they will create just branches in time, then what is it at stake? It cannot be rewritten because Deke didn't disappear, and if they could just rewrite history, then they could just go in the past and kill the agents when they were babies, but that wouldn't impact the future either, so in some form of thing, the Chronicoms know they cannot change time just like in the movies.
But Simmons and Fitz come from a future where Earth was colonized. Just remember, they were gone for an undefined amount of time to figure out how time travel works, and they didn't even find out. I HAVE to take Route A now, they saw the aftermath of the Chronicoms actions, time traveling or not, they KILLED their friends, Quake was killed, the world was conquered by the Chronicoms, and they just had to save them by time traveling in 2019, so they had to take them out of time and fight off the Chronicoms from doing whatever they wanted. So it is tricky but it will all get solved soon, but no. They are not rewriting timeline, they just cannot.