I don't know, I would prefer the devs' limited time and resources be put into the mainstream FFXI.

They probably do have the old versions' archives but it's not as simple as just throwing it on some server somewhere. People will still expect support, and if it catches on they'll want seasonal events and other content ported to it... And isn't there a lot of long term progression goals in FFXI right now for people that want to do that kind of thing?