Yes, maybe it's not supposed to be an earth shattering surprise? Perhaps for the characters but not for the audience. I, along with many other others thought the bread crumbs left throughout TFA for viewers were pretty obvious in telling that Luke/Rey and father/daughter.
they did a bad job setting it up if it's not supposed to be a big surprise. they fanned the flames about her lineage multiple times in TFA ("where do you come from?" "[bb-8 banter]" "classified, really? me too. big secret"). I doubt they would've done that if the reveal is just going to be what everyone thinks it's going to be. if it's Luke there's something we're not getting, it won't just be him having a kid.