This is really convincing, especially based on the "this area isn't available... yet" note. Further, I think more is revealed thanks to the Aldecaldo ending as well (I don't think I need to say this, but SPOILER WARNING)
In the Aldecaldo ending, there are three other things to keep in mind;
FIRST: Cassidy's bit of dialogue in the Aldecaldo epilogue:
"Bad thoughts are cheap, but they smear over the truth like mud. You think you'll run outta fuel before the stop? You will." To me, this is a sort of meta-comment in a way; if you
want the end to be that V finds no cure, no hope in the end, then V will succumb to her limited life. However, there are so many things pointing against that and the struggle for survival is a tough one, so we have to, in a kind of ironic way, come to terms with the fact that V
will survive. V survived Dex, V survived Johnny, V survived Arasaka, V survived Soulkiller, and V survived Night City, so certainly V will survive this.
SECOND: The data shard of The Iliad:
"if I abide here and war about the city of the Trojans, then lost is my home-return, but my renown shall be imperishable;
but if I return home to my dear native land, lost then is my glorious renown, yet shall my life long endure, neither shall the doom of death come soon upon me. "
I do not think there is
any possible reading of this that would lead one to believe that V is doomed no matter what. V is
leaving Night City behind, not giving up on hopes of becoming a "legend", but realizing that dream in and of itself was an illusion, was the false promise of eternal life, just as Soulkiller and Mikoshi was for so many others. It is leaving, returning "home", which for V is returning to their new home in the "native land" of the badlands with the Aldecaldos, that ensures V will live a long life, and that "the doom of death" shall not "come soon upon (them)".
THIRD: Misty's final Tarot reading (sorry for cropped image, took screenshot from a youtube video because I forgot to in-game)
Using this website to find the meanings of the cards:
The Chariot
"The Chariot predicts success in a specific situation. The success will be clear and powerful, transmitting complete satisfaction and glory."
The Lovers
"The symbolism of the card is obvious: love." (based on what Judy says when giving a Tarot read before Panam arrives, also has to do with family, friends).
The Sun
"The sunlight returns to illuminate our path and eliminate the perils of darkness. Now our path is brighter and free from dangers. A period of serenity and happiness awaits. After difficult periods (darkness), everything is taking a turn for the better. Great personal gratification because a positive moment follows less fortunate ones."
Knowing Misty's tarot readings have, in the game, been accurate, implying that tarot can work to divine the truth of the future, and knowing that the tarot readings at each ending is different, implying accurate readings for each ending, we confirm that the Aldecaldos ending is the most straight-forward, illuminated, direct path to ensure "success in a specific situation", such that in the end, "everything (takes) a turn for the better".
So yeah, I would bet that, at least in one major DLC, there will be expansion into Arizona, likely regardless of what ending you picked so long as you didn't lose yourself to cyberspace or suicide.