I'd be against a re-cast. They could use archival footage and use her character in a different way (flashback, speaking to Kylo or Luke). The fact they've dismissed the idea of CGI immediately is interesting. Makes me think her role in IX wasnt critical, despite the director previously saying otherwise.
When I was waiting for TFA to begin for the first time, I was nervous. They could have screwed it up. But the opening line of the opening crawl made me realise they got it right: "Luke Skywalker Has Vanished" so I do think the crawl for IX will reference Leia in a similar way "Leia Organa has died". it will be seen as something that threatens the entire movement. In that way, Leia's importance to the saga will weigh over the film without her having to be involved.
And I do hope they keep Luke alive. I sort of thought they'd keep him alive throughout anyway. Instinctively you think he's the Obi Wan role and would die in VIII but do we really want all three lead characters to die? IX should end in a homage to Jedi with Luke (and Rey) gazing upon their fallen friends...and somehow referencing Leia and Han at the same time.