I think it's always been safe to assume that Spider-Man would be back in action fighting alongside the Avengers in Joe and Anthony Russo's Avengers: Infinity War. However, there's been no official confirmation until now, so if any of you had any doubt, Tom Holland confirmed it in an interview with Vogue. After all, the last we heard from Holland on the matter was that Spider-Man's inclusion in the film was "all up in the air."
The first tweet below shows the full article in another language and the second one show the roughly translated confirmation in which Holland said:
"It is they who convinced the Marvel (Downey and Evans)... the producers wanted to be sure that I was the right person before you entrust three films over the next four years, including Avengers: Infinity War."
The next two Avengers films are sure to be something insanely epic. We only know that there are going to be a ton of superhero characters involved, including a team-up of the Avengers and Guardians of the Galaxy, and that they will be battle Thanos. I can't help but think that this is going to be an intense film, and I imagine that when they battle Thanos, not all of the heroes will make it out alive. Who knows, maybe Iron Man and Captain America will die holding hands.