Do you think there could have been peace between House Targaryen and House Blackfyre? Maybe between the end of the first rebellion and the deaths of Haegon and Aenys?

Probably not. After the first rebellion, you still have the feeling among Blackfyre supporters that they almost won, and that they would have if not for Bloodraven’s cowardly kinslaying, and you have a lot of exiles abroad and punished rebels at home who want their lands back. 

Maybe, maybe, if the Golden Company and the Blackfyres had decided instead to restore the Valyrian empire, unite the Three Daughters, and fight to conquer Volantis, you might have seen them eventually stop caring about Westeros in favor of their new lands in the richer and more sophisticated east. But that’s a pretty big maybe.