WHAT?!?!?!?!?!?!?!
Dude, I said this last year
Rogue leads up to the rebels getting the plans and Vader chasing Tantive IV. There was ALWAYS a chance we would see a young/digital/voiceover type Leia/Droids cameo. They're on the damn ship that has the stolen plans when Vader chases them down.
You didn't know the timeline Rogue One slots into all this time? From jump we've known it would lead immediately up to the opening crawl of Ep IV.
The larger point is they are not going to use an early 20's woman to be the lover of a now 60 year old Luke Skywalker. If Rey was Luke's daughter, you take away the explanation of where her mother is, having Jyn play some old lady in Ep 8 is ridiculous.
Rogue is it's own story, just before the Saga picks up where it did, no sequels, no spin offs of it's own, but there are surely characters that could appear in other films, like the Han spin off, or maybe a future Obi Wan, or Fett spin off, etc.
You gotta let the Jyn one go. Rey being Luke's is entirely plausible, Jyn bein the mother is not, let it go man.