I am very surprised to hear you say that the man I knew is not gone. That actually is good to hear, because from what I can see, Elvis has completely left the building and checked his brain at the door. The couple times we did get together, though, I saw a few glimpses of the man I thought I knew. At the moment, hope feels like an enemy, so I won't get my hopes up that he's still in there. I know H is on his own journey and in his own crisis and he has to want to come out of it, if he ever does.
I think a better way to think about it is that he has been captured by aliens and is now orbiting the earth on a space ship. His body is still here but the brain you once knew is not on this planet right now.
IF he returns then you will see a new person with some old traits and some new ones.
But until that happens best to LET GO and let him have his crisis.