Board Thread:General Discussion/@comment-26838855-20190803131136/@comment-1894786-20190808231246

I'm only going to bring this up one last time, but yes. Agree to disagree.

Hulk's explanation to Rhodey about "changing the past cannot change the future" clearly establishes alternate timelines, and clearly sets up that every single trip we see is in fact a new branch off of the main timeline.

The Ancient One's explanation to Hulk about branches is only in relation to possible negative futures opened up by removing the Stones, from an already existing branch (in the Ancient One's hypothetical, this was likely alternate 2012 being vulnerable to Dormammu in 2017 because Hulk didn't return the Stone). We know she must be talking about an already existing branch, specifically her branch, because she explicitly is talking about the removal of the Stone, and not about time travel itself.

Returning the Stone does not clip off the branch and reset the timeline, it only makes it so that branch is no longer facing a chaotic future due to not having a specific Stone available (Cap returning the Stone ensures that Strange will be able to lock Dormammu into the time loop and scare him away).

That is how Cap can live a life in an alternate reality with Peggy. That is how 2012 Loki can have a Disney+ series about his life after escaping, despite Steve being clearly instructed to return the Stones to the exact moment they took them from (meaning the timeline would be reset before this Loki could ever do anything noteworthy), as that is what Bruce promised he would do to the Ancient One.

Also, it would take quite some time for Thanos and Ebony Maw to reverse engineer Pym Particles, gather the entirety of Thanos' army in one space and shrink everything down in order to go to 2023, no matter how smart they are and how much tech they have. If Steve returns the Orb even a second after Nebula leaves the Temple (when they got the Stone), that only leaves a few hours at most for Clint and Natasha to get the Soul Stone and for Steve to return it, obliterating this timeline.

That is how I've interpreted the rules as laid out by Endgame, that is how I've seen most people interpreting the rules, and I believe that's how the Russos are interpreting the rules and why they've stuck with the Alternate Timeline theory so vehemently.

Whether or not Markus and McFeely interpreted the rules that way when they wrote them (which clearly they don't, since as of SDCC they still maintain it's a loop, and even brought in a science consultant to back them up), it's honestly no longer relevant. The final product is out of their hands now and it's in the public consciousness and can be interpreted in any number of ways.