While there were many surprising decisions at the end of Avengers: Infinity War as far as which heroes we lost and which ones survived, there was one very clear pattern that emerged. All five of the characters who made up the original Avengers survived. While the exact fate of Jeremy Renner's Hawkeye was unknown at the time, this pattern (and the fact we knew Renner had filmed scenes for something for the two Avengers movies) led many to believe Hawkeye had lived, something which has since been confirmed. In the lead up to Avengers: Endgame, Renner appears quite focused on his original co-stars, as he has continued to share pictures to Instagram focusing on these six heroes.
A few days ago Jeremy Renner shared the six character posters of the original Avengers team that were released as part of the 'Avenge the Fallen" series. He also gave a shout out to his "A6" on Instagram. While there are several other characters who will certainly play important parts in Avengers: Endgame, one certainly believes these six characters will still be the ones at the center of it all. The Marvel Cinematic Universe really took off with the original Avengers film, and Endgame is expected to be something of a conclusion.
And of course, Jeremy Renner knows some things that we don't. While we expect that Endgame will likely be the final MCU movie for Robert Downey Jr. and Chris Evans, and possibly others, Renner would, one assumes, know for sure if that's the case. He not only knows if they're leaving, but assuming they are, he knows how it will happen in the film. It could be part of the reason he's celebrating his old friends, because this is his last chance to do so in this context.
It's not all super serious, however. Before sharing the picture of all six Avengers looking focused and committed, he shared a very different picture, showing the six Avengers actors being silly and ridiculous. Check it out.
Of course, while most of the focus is on the big names of Downey and Evans, we don't really know what the future holds for the other four actors either. We know a movie based on Black Widow is on the way, but that one is expected to be a prequel, so that doesn't mean that character is any safer. The Avengers will likely move forward, but they will almost certainly look very different when they do. Just which of these six characters will we see again, and which will we be saying goodbye to for a final time?
Is Renner being nostalgic because he's one of the people going away? Who knows. I certainly won't be happy to see any of these six characters go.