You are talking about books. Disney has stated they are going original. So you don't know who they plan to have as part of the Jedi Order in 7. I know the nerd-tears will be flowing strong with people if people from their favorite books are not even mentioned.
As for popping up out of nowhere, has it dawned on you that Jedi are not supposed to have offspring in the times. Episode 7 might have new rules since it's being rebuilt after the fall of the Empire in RotJ. So yes, they did pop up out of nowhere a lot of times.
And everything you said about why she can't be used in relation to 66 can also be applied to Kenobi. Yet, he was living on the planet where Anakin was born with one of his children nearby.
Yes I realize that they aren't suppose to have them, what I mean by popping up is. Old Jedi from the old JO coming out and showing themselves. Yes he was living on a planet, that Anakin didn't want to go anywhere near.
I know Disney is going original, but following the movies anyway any surviving Jedi were hunted down, just because they weren't shown doesn't mean that its true. But anyway...we shall see what happens.
Besides it isn't like, there can't be other Force Users out there who can't be trained as Jedi which is what Luke did regardless of age.