During an interview on Jimmy Kimmel Live, Robert Downey Jr. was asked if he would appear in Spider-Man: Homecoming (Marvel Entertainment's first Solo Spider-Man movie). RDJ said "Perhaps, I don't have a contract." So while this is all speculation at this point, RDJ did admit to being a fan of Spider-Man growing up, saying "To me, Spider-Man was my whole deal. He was funny and young and cool." So this might be a great sign that RDJ could possibly have a role in the upcoming Spider-Man Movie. Especially since Stark plays a key role in Spider-Man's life during Civil War. Maybe the Spider-Man movie is pre-Civil War and RDJ will be playing the role before he fought Cap and his team. It's not like it happened out of nowhere. There are three key moments that Tony Stark plays in Peter Parker's life during Civil War. While it may not go down like this, it could happen in much faster fashion.
Tony Stark, The Mentor:
Before the Marvel Civil War started, Tony Stark took time to invest in Peter Parker the person. Peter spends so much time as Spider-Man fighting villains we sometimes forget that he's actually a genius. In most realities he created the formula for the web fluid and also spider trackers that allow him to find people via his spider sense once he's in close range of the tracer he's planted. Since he was so intelligent, Stark took interest in Peter and recruited him and Tony told Peter he wanted him to work for him. Peter agreed. Peter would follow Tony around the country watching what goes into being Tony Stark outside of just being Iron Man. The trips to court, conversations with the government and the press, etc. This was all grand and brand new to Peter. All of this blinded Peter to what was really going on. What Peter didn't realize is that Stark knew about the Superhuman Registration Act (SRA) and that drafts of the law had been made. So while it may have seemed like he was helping Peter, Stark was doing it for selfish reasons.
Tony, The Hustler:
People rarely say no to Tony Stark. He's smooth, funny, charismatic, and rich. To top it all off, he gave Peter a new costume with technology in it. No longer did he have to wear the classic red, blue, and black costume. He could sport the Iron Spider yellow and red (it was made by Stark; what colors were you expecting?). All the new gadgets and tech in the costume was helping Peter become a more efficient hero. Every time Peter had an issue, Stark would smooth things over and give him something. It makes sense, though. When you're dirt poor and a rich guy gives you a job, you usually accept. Especially when this guy is your friend and your mentor. There's no way he'd betray you.
Tony Stark, The Betrayer:
Eventually, Peter realizes that Stark had not only been lying to him, but he's also been using him this whole time. Stark is a futurist. He knew that getting Spider-Man (a guy who spent most of his career on his own and hiding his identity) on his side would be key to getting people to join him and sign the SRA. It's highly doubtful that Spider-Man will reveal his identity in the movie, but if Tony Stark is in the movie, look for Stark to manipulate the very young Spider-Man into doing everything he can't do himself. It's unfortunate that Reed Richards can't appear to give Peter the talk that helped him sway from Tony Stark's to Captain America's side. It was a very cool and deep moment that would have translated great into movies.
At the end of the day, the planning for this movie is still in its infancy stage. So much could happen between now and the time it's time to start filming. For all we know, The Fantastic Four could come back to Marvel and add more to the Spidey movie. Or RDJ could play a completely different Iron Man than the ones we are used to seeing in the comics. One thing is for sure, we all hope to get more Iron Man and Robert Downey Jr. any way we can.