27ages of discussion so I hope this hasn't been mentioned.
Has the idea of Rey being a force baby been discussed? Ala Anakin immaculate conception via midichlorians. I just don't want to think JJ went with Luke being her father, I guess the force-baby route feels contrived as well but I don't think Luke or Anakin were ever actually the "chosen ones" who brought balance to the force. If the Jedi truly believe in the concept of "balance" there needs to be the rule of 2 sith and then the Jedi to balance.
When Anakin flipped and killed all of the Jedi, the force swung dramatically towards the Sith. When Luke converted Anakin back to the side of light and Anakin killed Palpatine. The balance of the force swung back dramatically and left a hole in the dark side for Snoke and the Knights of Ren to fill.
I want to think that Rey and Finn will end up representing two sides of the same "neutral" coin and bring true balance to the force.
One could argue that Annakin brought "balance" to the force. When he is very young there are lots of Jedi, but only 2 sith (as is normal).
After Palpatine and Annakin slaughter the Jedi, there are really only 2 jedi left, and they go into hiding.
Of course, this allows the Empire to grow, but technically the Empire isn't part of the force.