Possible spoilers though really stuff one would completely expect after having seen TFA. I'll put the quote in spoilers.
http://www.hollywoodreporter.com/hea...-future-960849
She'd already filmed her parts for Episode VIII, but if her parts in Episode IX are substantial or critical, then they would either have to rewrite the script (either to change the plot and have Leia off screen for some reason during the movie, or to have her die in the movie, an an off screen death would be a terrible way to honour Fisher), to recast Leia with another actress if they think the script would be too diminished by rewriting it, or to do Leia as a CGI character.
Out of those options I think I'd prefer a different actress. Maybe one that's endorsed by Fisher's estate to make it more palatable to people who might otherwise be upset by it.
I don't think a digital effect would be what Fisher would want, and if it's a large role it'll be more difficult to do well than brief chunks. And I don't think Fisher had such a big ego that she'd want her face to be Leia and no one else. I don't think a digital actor honours a passed on actor, and it feels like a money decision rather than a story decision.
Rewriting the script I don't like because Leia is a badass and deserves to be part of the story, and an off screen death or a digital actor death I don't think does justice.
So the only thing I think I would want is a different actress. Would that be too hard to take for fans though?
Or I guess they could do some combination of minor re-writing and casting, have a different actress like get Fisher's daughter and have some in-universe reason she's young again or something.
I hope it's not too soon, but I don't feel the idea is like moving on but rather how to best honour Fisher.