I still think two versions of this film's script were penned almost a year ago. One with Spider-Man and one without. As soon as this news broke, the movie we were almost certain to get ended up in the shredder.
I completely agree, however I take it a step further. I believe they had this planned out the whole time. They're freaking Disney/Marvel, I don't think they doubted they would make a deal for even a second.
So no, I don't believe anyone's role will be changed for spiderman, as I think he's been in the script this whole time.
Now for my theory, I think spidey will be 16 and already have his powers.
He will be fighting crime in like a ski mask or something similar to what Miles wore when he first started out.
He will first side with Captain due to how much he looks up to him or something.
Tony will come along they bond etc. and Tony will make him the suit we all know and love, explaining how a kid could make such a complicated suit.
I don't think they will do the Iron Spider.
Now he's torn but eventually sides with Tony, black panther will side with Cap.
Spiderman is about to take off his mask or what ever the mcu equivalent ends up being and cap gets shot before he does.
Everyone is left shocked, etc. While spidey gets to keep his secret identity.