andrew has said loud and clear in a couple comic con interviews he thinks peter parker should be a kid, not an adult,so they shouldn't do too big of a time jump, he's saying it'd be nice if he were in 3, not 4 movies... he's clearly saying he doesn't want to do with without actually saying it. it's not a matter of him pulling off looking younger or how old rdj is, dude simply doesn't want to spend half of his professional career being in a franchise, and who can blame him. he's barely had a life since this whole thing started, and it's only been 3 years.