Or he could dream about Evie in the way he hallucinated briefly about Janet in the cave during the last update. The ancient Greeks used to practice oneiromancy, i.e., divination by dreams, to predict the future and used similar means to commune with the spirit world via lucid dream-like states; natural, meditative, drug induced, and sometimes as a result of an injury and such like. So it's quite possible for the sake of the narrative for the Henry to interact with Evie, while in a dream state, so vividly that it would seem to him (and us) not much different to a physical experience. And maybe by the end of the game some occult means will have been discovered via the legacy magic of the Tikpac, or whatever, to spring Evie out of her crystal prison and back into her body; indeed, thinking about it further, Madalyn could quite possibly be pursuing much the the same thing, or something very similar, with a view to reincarnating Father Parker/Daemalius back into the world.
I'm not sure that even NLT knows yet how his epic story will eventually play out.
Funny that Henry hasn't asked Evie whether he will ever meet Ash in the future.
(If not he will be able to keep Ash's camera and use it to snap any number of post-coital girls in the future without any worries!)