I agree, it's not 100% sure, but on a personal level I think it's 100% certain (it's not even about being right or wrong for me, I just love to speculate about these kinds of things).
On the her vision, I do find it interesting that Obi-Wan is calling her out. Specifically mentioning 'Rey'. Yoda has a more generic (re-used) line for example same as Luke. Then there is the whole theory that her Force vision has some overlap with a vision that Kylo has about 'a girl'. And he's shown holding what looks like Obi-Wan's lightsaber in the vision:
The theory (
origin of the theory) is that Rey has a vision about Kylo upon touching Anakin's saber and Kylo has a vision about a girl left on Jakku upon touching Obi-Wan's saber. Couple that with the tweet that went out on the official Star Wars twitter a while back:
It's looking like that it's going to be a plot point in future films. And finally I think Kylo's real name being Ben is going to have a more emotional pay-off then it just being his name, from a story point of view.