Maybe The mid Scene should feature Ayesha and the Soneregin being revealed to be The Universal Church of Truth worshipping Magnus, Who might appear in the scene like Thanos. and Maybe The post credits scene should feature a brief humorous scene, to complement the generally lighter tone, What do you think that humor scene would be,AnyWay?

Why should he apologize for a CBM franchise with 6 great movies, 3 very good movies, 3 solid movies, 2 meh movies?
Fixed
If anything Zack Snyder should apologize for ruining the two most iconic comic book characters.
"Never tell me the odds!"- Han Solo

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Why should he apologize for a CBM franchise that's actually great?
"Never tell me the odds!"- Han Solo

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A certain half Kree girl showing up and convincing the Guardians to come to Earth

Guardians heading to Earth
"Faith is my sword. Truth my shield. Knowledge my armor." - Doctor Strange
IRoadA

The last one.
Whatever you are, be a good one.

I think you can absolutely rule out any teaser for Ragnarok or Homecoming, for two reasons:

1. They already were teased at the end of the last 2 MCU movies, and the MCU has never teased the same movie twice since Phase 1, when 4 out of 5 of the teasers were for The Avengers.
2. The MCU has never had an end credit teaser for a film less than 9 months away, and it is usually for a film at least 12 months away. Homecoming and Ragnarok will be only 2 and 6 months away when GotG2 releases.
   Not counting Doctor Strange teasing its own sequel, the last 3 end credit scenes were for Black Panther, Homecoming, and Ragnarok. By that pattern, it is clearly Infinity War's turn next. In the first Guardians, both mid and post credits scenes stayed within the universe of that film. I think the mid-credit scene for GotG2 will keep to that, but then I expect the post-credit scene to get the ball rolling and get people excited for Infinity War. I expect it to show that the Guardians, or at least some characters from Guardians will somehow be getting involved in that war.
   I also will predict that Homecoming will end with a teaser showing Spider-Man getting involved with Infinity War. The status of that happening is supposedly up in the air at this point, but I think they will try their best to make it happen. Civil War teased Spider-Man for Sony, and I think Sony will return the favor for Disney, to the benefit of both companies. That will break the rule of one teaser per movie, but just like The Avengers (4 teasers), Infinity War is a biggie and deserves more than one.
   My life has major plot holes.

I expect Nick Fury to make an appearance and sought out The Guardians help in searching for a missing "infinity stone " (The Collector has it). He tells them that a powerful man is looking for it and the GotG decide to help him find it before Thanos does because the Guardians are aware of who Thanos is (they fought his general and adopted daughter) and they know how dangerous he can be if he has all 5 rings. and also, This movie would have nothing to do with Thor3, I doubt it will get mentioned. Thor and Iron Man movie generally do not link to the avengers franchise (only captain america movies) thus why Thor made an appearance on Doctor Strange so the link is already there.
Life is a joke, but atleast its a good one.

Two scenes, similar to the first movie:

1. Groot teaching Drax to dance
2. Heimdall telling Odin(Loki) that Thanos is up to something

Cops tell jokes too OldboyMcclane.
"Unicorn, mermaid, vampire,sorceress! No name you'd give her would surprise me i love whom i love"

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Thor & Cap both teased the first avengers.
I think they want to hit a homerun with Thor, I think they'd be wise to promote it as much as possible.

Thor Ragnarok was already teased in Doctor Strange and its unlikely they will tease a movie twice. Marvel has never done this before in the MCU.
Spider-man Homecoming was also 'teased' at the end of Civil War and is too close to Guardians vol 2 to be teased. The full trailer will be out by then.
For Avengers Infinity War it may be too early. It can happen since its indeed a year from that movie coming out. But there is still some story to be told before that one comes out.
In my view there are two options.

1. Not so likely: A tease for Black Panther which comes out before Avengers Infinity War and hasnt really been teased in the MCU unless you count the Civil War mid-credit scene as a tease.
2. Most likely: A scene that is a Guardians connected scene which doesnt really tease anything at all. Just like the one with Howard the Duck in Guardians vol 1.

Aren't your first two ideas Infinity War teases?
My life has major plot holes.

I don't think it will be an Infinity War tease like some of these people.

• I think it might be likely that Hela hands the Soul Gem to Thanos
• Possibility that Warlock awakens within the gem
• Also possible that we see a Hulk as a gladiator type of tease as well.

Thanos attacking and/or destroying the Nova planet perhaps

Warlock please

I agree, but I also have come to think that Adam could show up at the start of Infinity War just as easily. There is no real reason he has to be introduced before then, but of course I'd love it if he was.
You also have to accept that he may not show up at all.

If he's going to be used at all, this would be a perfect opportunity to show Adam Warlock, if he isn't already in the movie.

Maybe another look at the Adam Warlock cocoon.

No, I don't give this one ounce of a chance of happening.

How did they hear about his team?
Being that they are comprised of heroes from not just Earth but other planets/realms and the fact that they, like the Guardians have been in contact with Infinity Stones, it's very plausible that someone lets the Avengers know about the Guardians.
How did they know how to call him? Does he have a cell phone or something?
He has a communicator on the spaceship. Shouldn't be too hard for someone like Tony Stark to figure out how to get the signal into space.
Victims, aren't we all?