The dirty little secret about how multi-media franchises work and why someone could pull off something as obstinately obnoxious as retconning Rey's parentage for the third time in three films is this: it would exponentially increase the products you could make with major, significant characters.
If someone actually did retcon Rey back into being Luke's descendant, than Rey herself becomes a more significant, must-watch character for the franchise, anyone else involved in the circumstances of her birth becomes more significant and must-watch as a character, and it likely reinvigorates Luke as a character post-ROTJ and lets you tell new, "more epic" stories
with him.
I could see like two to three major shows, cartoons, video games or movies you could birth from that right off the bat; that's how valuable the Skywalker Family IP is, and why making Kylo the only, doomed family member was unequivocally a bad business decisions, whether one thinks it was a solid artistic decision or not.
If this was comics, I would seriously place money on either that or Luke being resurrected as inevitable editorial decisions. As a film-based franchise, I think it's very unlikely because of professional embarrassment and conflict it would create for people who backed TLJ.