I mean, they could still do it if they were that adamant about having the Shaw-Ghost in the film. Kylo could just say, “Grandfather?” and the audience would put two-and-two together.
But then again, JJ did have Ewan come in and do a few lines, like “Rey”, which they didn’t use, and “These are your first steps” which you can hear at the tail-end of Rey’s lightsaber vision in TFA. It’s also possible JJ was convinced, by public opinion or collaborators like his co-writer Chris Terrio or Kathleen Kennedy, that including Hayden could help tie the trilogies together and make IX feel like a culmination of all nine films, rather than just the OT.
But like I said, I would be surprised if we got a scene of Force-Anakin passing down some exposition to our heroes. A similar, brief cameo to what we got in ROTJ seems a lot more likely to me.