tldr. I read the last paragraph. I find it very unlikely they are going to be setting up Kang to get an edge on Thanos, in my opinion, no one short of Warlock and guys like that should be able to out smart him. idk what else you wrote. But consider this. After you write something like this, If you can, try to paraphrase it all before posting, because people are not going to read this dude. It's too long.
Also consider the fact that most characters from the infinity gauntlet saga may not show up
TBH i really think, like a few others, that Thanos will have to be powered down a little bit to work as a character, and may have to remain in the shadows until Avengers 3. Only being briefly included in Avengers 2 and GotG until phase 3.
Additionally this would see many villains working together under Kang's plan against Thanos, and Kang only has a slight edge on Thanos because he comes from the future. A time when he knows what has already occurred. By his "like the Pharaohs of old" line in Avengers I think Fury already knows Kang has been all over this timeline... an incident happened in the past and Kang escaped to some unkown time with Ultron. Only to return with Ultron in Avengers 2.
Warlock comes into it later as the alternate version of Magus, but Magus gets introduced first in GoTG and is present in this side of the movie multiverse first.
Marvel wanted Silver Surfer and some of Fantastic Four's characters back. They may be covering up the fact they actually wanted the rights to Kang... harder to get because of the relation to Dr. Doom and Mr. Fantastic. When everyone else thinks they want Galactus (could still have him in the works too, because FF may not want to use him again).
There are other time and dimensional hoppers plus other protecting forces of the universe subtly assembling people against Thanos.
One of them may take young Pym from the 60's to the present.
And Kang and his alternate version can travel to a time when Thanos doesn't suspect things. Pop in and out of the timeline, like Loki can skip dimensions and have copies of himself in a way. The Magus will come to serve Thanos and survive GotG, but Nebula and Gamorra appear to be dead for now. And the other is actually a powerful ally too. Which means no one ever gets an edge on Thanos for long... but Kang has an advantage in that there are infinite versions of him that can come back from the 31st century and other parts of the multiverse.
That doesn't mean they won't adapt things while morphing them slightly and staying true to the comics-- having Thanos come out on top on one hand... and having all the other heroes and surviving villains have to team up to defeat him and save the universe/multiverse with the other hand...
Avengers 2 would then see Kang set Ultron, Red Skull and the masters against the Avengers to take the scepter back from shield after failing to steal back the cosmic cube from Asgard by using Malekith and an army from all across time and space... freeing Loki in the process. Red Skull may have traveled to a different dimension, but has he traveled to a different time?
Is Ant Man still set at least partially in the 60's?
Will GoTG be in the 21st century or 31st century... or both?