When you say flight, are you talking about gliders? Or are you talking about propelled flight? Just need a bit of clarification before I attempt tackling this question. :)

Sorry, but your submission has been removed because we don't allow hypothetical questions. If possible, please feel free to rephrase the question so that it does not call for such speculation, and resubmit Otherwise, this sort of thing is better suited for /r/HistoryWhatIf.