As fair a request as this is, what is not apparent to players which makes such an idea highly unlikely is that most of 1.0's storyline has been decanonized by ARR (because 1.0's original story, lore and setting ideas were originally written by a staff member who no longer works for SE) - the only part that is still 'canon' is the Seventh Umbral Story from when Yoshi took over as producer and director which served as the lead-in to ARR. The original 'starting city' storylines and the abruptly truncated 'Path of the Twelve' story featuring Minfilia have been cannibalized for ideas and concepts for ARR's story anyway with the basic idea repeated in ARR's main scenario, with some elements no longer considered 'canon'.
Also, you have to remember that one of the reasons ARR was even created was to replace 1.0, it's a reboot rather than a straight sequel/continuation to 1.0. If there was any theoretical single-player tie-in game or expansion pack to ARR that was set pre-Calamity in the Sixth Astral Era, it would just feature ARR style zones and ideas (most of the zone maps are wildly different from the 1.0 maps,because one of the main complaints of 1.0 was that the zones were too large, empty and monotonous), and would not restore 1.0's environments, maps and models (the later are already used in ARR anyway), and would actually turn out to be a different experience to what 1.0 was, which would defeat the purpose of what players want.
Before you pass judgement, SE themselves even trialled a 'restored' 1.0 service running concurrent with ARR after the original shutdown in the last few months of 2012, it was fully dependent on player numbers, which, sadly due to the ARR Alpha Test running at that time.... barely saw any use at all, and SE terminated it for good on December 31st 2012. Which is a shame, as Yoshi himself said that the game could continue "more or less indefinitely" if there was enough interest. Player numbers in that brief time though... saw to it otherwise. And I'm pretty sure this has dissuaded SE from any further attempts to restore 1.0 in any form sadly.
No, it's time to accept it, 1.0 is gone and is never coming back. Players had their chance to keep 1.0 active, and they ignored it. It's stories and concepts are living on in ARR which is it's replacement. Yes there are things in 1.0 that actually worked well that I would love to see return, but 1.0 itself, is ancient history. Let the past stay passed. Let's look to the future.