Well, Hollywood tends to not always be trustworthy. But I don't think screwing Rey over would be fixed by making her a Skywalker. It would just reinforce the notion of needing to be related to someone in order to be a good character, yet wouldn't fix any of the actual problems with her, or with Finn
And there's nothing wrong with a tragic ending. I don't buy the idea that the sequels are ruined because the Skywalkers didn't get the cliche happy ending