I don't believe that's necessarily true. I have the TFW art book and the caption for those pictures doesn't say that a "force ghost Anakin" was ever in the script. Much of the artwork (in fact, most of the coolest pieces in my opinion) was created to inform the script, not the other way around.
They specifically asked the artists to just create anything and everything when pre-planning Ep 7 just to flesh out the new universe visually. Most of it didn't make it in the film and much of it was never created based on any script needs, but rather to just see whatever cool stuff the artists could come up with. My guess is - but again, the book doesn't say either way - that the concept artist (Ian McCaig) for the linked Anakin created it on his own initiative.
Highly recommend the book to anyone and everyone!
I haven't, though some of the links from my original posts on it have a bunch.
I also think that this book might have some stuff too: https://www.amazon.com/Art-Star-Wars-Force-Awakens/dp/1419717804
I have this artwork! It shows up in the TFA artbook, would highly recommend.
Why are people treating this like it's a new image that's never been seen before? It's a piece of Thom Tenery's work from the TFA art book released last year.
These are from The Art of Star Wars: The Force Awakens
Released on 18th. Probably with retailers now.
This book has more info about the homage (p. 84): http://www.amazon.com/The-Art-Star-Wars-Awakens/dp/1419717804
The Art of Star Wars: The Force Awakens https://www.amazon.co.uk/dp/1419717804/ref=cm_sw_r_cp_api_kj0HybCVCEZX1