The remaining two movies, which you might already know of if you've been following the news, but anyway, here it is...
A quick update before we start:
I've just found out that Ant-Man will no longer be part of Phase 3, and will act as the last film in Phase 2 instead.
Avengers: Infinity War - Part 1 (May 4, 2018)
Avengers: Infinity War - Part 2 (May 3, 2019)
This is the big thing, the massive event where everything in the MCU will culminate in. Beginning in Phase 1, where we see The Tesseract & Loki's Scepter, moving on to Phase 2 where we are further introduced to The Aether & another yet unnamed Infinity Stone (purple orb) in Guardians, and into Phase 3, expect more stones to be revealed, where everything will culminate in a battle against the mad titan Thanos, who in the anouncement teaser, is seen wearing the Infinity Gauntlet with all the gems attached. Again, the title seems no less conspicuous, clearly hinting to the fact that this will the biggest of battles, with the involvement of the Infinity Stones.
The battle is probably going to be so big, that the whole arc is to be split into two parts, with a one year gap in between, which will not feel too long once the epic battle takes place. And a film of this epic scale allows the possibility of more new characters to be part of the fight, and more importantly, even the Guardians of the Galaxy. Not only is the movie scale & scope big enough to fit all the characters, but even the story would probably allow the settings to take place in the cosmos, other dimensions, realms, etc. It feels massive, but I hope (and I do have the sheer confidence) that there will be a strong emotional plot holding all the action & settings together.
Releasing in May 2018 & May 2019, the journey is still quite a long one. (But the excitement & anticipation is surely high...and will be even more so...)
Phase 3 - Overall Thoughts
In a quick glance, there seems to be more new character standalone films than the sequels. Equal in numbers, though, if we take into account the two Avengers films. However, the way I see it, Phase 3 may well be the end of the line for our original Avengers: Iron Man, Thor, Captain America. Because they seem to have no plan to go beyond a trilogy for their respective standalones, and by the end of Phase 3, would have done three (or four) Avengers films as well. Add to that the fact that the actors' contracts would have been exhausted by then. So, unless Marvel has another big plan for these characters going forward (crossing fingers), it does seem like these characters won't go beyond Phase 3.
So, in the end, it will feel like Phases 1-3, will be like the big trilogy that encompasses the story arcs for our original Avengers. Afterwards, stories told may be of the newer characters introduced, and the Avengers roster might have changed completely by then. It's not all bad, and yes, by then, I would still have complete faith in Marvel, but it's just sad to feel that the stories of the original Avengers may end by 2019.
Of course, this is just my speculative vision, and there's still hope for them to appear in Phase 4 and beyond. Chris Hemsworth won't be too old to continue by then, and Sebastian Stan should have 9 movie contract, so it's too early to cross them off just yet. And in this industry, anything can happen. From recasts to recontracts, anything can happen, and it's in their (Marvel) hands that we can simply place our trust that they will bring what's best for the fans and for audiences around the world. In the meantime, let us simply enjoy what is up ahead for us: The 9 movies in Phase 3 is sure to be one hell of a journey in a three year span...and we're not even done with Phase 2...next in line, Avengers: Age of Ultron!!!