There are different forms of flying that could be bestowed upon humans. Which kind do you mean? Would we have wings? would we be like Superman? would our flying ability be more like the Jetson's or, James Bond using battery packs or a belt that allows us to fly? People can already fly via say, a personal/private plane, a helicopter or by taking any flight we want via an airline like American, Southwest etc. that being the case, the things that have remained the same, will remain the same. The things that have changed because of our ability to already fly commercially or privately in our own planes would also remain the same.