This is actually my first post, if you think that there's wrong with my post, feel free to comment, Thank you
We knew in Thor: TDW that the Aether and Tesseract are 2 of the Infinity Stones. Aether is the Power Stone and Kevin Feige already confirmed that the Tesseract is the Space Stone.
What I thought about the remaining Infinity Stones is spread throughout the Galaxy(Universe). In Avengers, we saw Loki's Spear controlling many people(or turning them into his personal flying monkeys). What I thought about this glowing blue gem/stone in his spear is the Mind Stone. Since we didn't saw the spear being held by Thor and/or Loki in the end of Avengers, I assume that the spear is in the hands of SHIELD, and that spear will play a BIG part on Avengers: AU Story.
In Guardians of the Galaxy, I assume this orb in this poster:
will be an Infinity Stone. Either Soul or Time Stone.
In Doctor Strange,
I assume that the Eye of Agamotto will be either replaced by the Reality Stone or the Eye of Agamotto will be the Reality Stone.
and by that, we have:
Loki's Spear Geam: Mind
GotG Orb: Soul/Time
Eye of Agamotto: Reality
Avengers: Age of Ultron
Like I said earlier, the Loki's Spear maybe is in the hands of SHIELD, which I also I assume that it will be the Mind Gem.
In Captain America: The Winter Soldier, we may found out that the highest leaders/councilmen of SHIELD are the corrupted ones and they will gather all items related to the Battle of New York, including the spear.
and in Avengers: AoU, the non-corrupt SHIELD will hire Stark and Banner to create Ultron in order to create a Defense to avoid the attack that the corrupt SHIELD will make. Then, the corrupt SHIELD will use the Loki's Spear to control Ultron and it will be their weapon against non-corrupt SHIELD and the Avengers.
I don't know how they will handle that spear, but It's possible to control a Superior AI like Ultron to be evil.
Marvel Cinematic Universe Phase 3 Films
I'll skip into Ant-Man, Thor 3, and Doctor Strange. I will focus more on the possible 2nd GotG film, as they will introduce Adam Warlock. What does Adam Warlock have? the Soul Gem. In this possible sequel, we may found out that Thanos will be starting to gather the Stones in order to destroy Humans/Avengers. First, the Aether, which is in the hands of the Collector, next, The Tesseract, the Orb being held by Star Lord(in the poster) and lastly, Adam Warlock's Soul Gem. Making Thanos collected the 4 out of 6 Stones.
I assume that Thanos will destroy Asgard with the help of Odin(Loki), and get the Infinity Gauntlet in the Odin's Vault. Loki will help Thanos in order to destroy Earth. With the 2 Stones (Reality and Mind) located on Earth, Thanos will surely get the remaining stones. Doctor Strange and with the Avengers will try destroy the titan for the safety of mankind. Avengers will fail on defeating Thanos, killing major characters such as Black Widow, Hawkeye and Ant-Man. Captain America will gather the remaining Avengers and create a plan on stealing the deactivated Infinity Gauntlet and Stones. With the help of Thor and Hulk, they will successfully get only the Gauntlet. Feeling weak, Stark will wear the Gauntlet, activating it's power and Defeating Thanos. (in the comics, Stark is the first human to wear the Gauntlet)
That's it folks. Feel free to comment your thoughts. and we will wait until the next Marvel Movies arrive.