Progression server

so I have been playing lockjaw on EverQuest and I kinda missed Vanilla WoW... I got to thinking, what about a progression server? I have never played any part of WoW but Vanilla so what was there in the end?
in case you dont know what I mean by a Progression Server, I mean a server that starts at Vanilla then at a certain point, The Burning Crusades comes out and then WotLK and so on so forth, or in WoWs case, Patches... patches that release content.
So after I saw what the Nostalrius Dev team was able to to vanilla I knew I should ask.
So, the only problems I could think of is patching and legalities, but the solutions I thought of are... the P99 route (everytime there is a patch, tell the players at the login screen there is a patch needed and direct them to the game front page to find the download link and have the player manual download the patch directly to the game directory) or have a dedicated patcher for everytime you load the game that will patch the files for you.
Now what I mean by legalities is blizzard comes by and sees a private server that will eventually become live WoW... they will probably try to shut it down. I would say make the progression in the game so slow that it would take a long time (longer than Blizzards WoW took) per content release.
in case you dont know what I mean by a Progression Server, I mean a server that starts at Vanilla then at a certain point, The Burning Crusades comes out and then WotLK and so on so forth, or in WoWs case, Patches... patches that release content.
So after I saw what the Nostalrius Dev team was able to to vanilla I knew I should ask.
So, the only problems I could think of is patching and legalities, but the solutions I thought of are... the P99 route (everytime there is a patch, tell the players at the login screen there is a patch needed and direct them to the game front page to find the download link and have the player manual download the patch directly to the game directory) or have a dedicated patcher for everytime you load the game that will patch the files for you.
Now what I mean by legalities is blizzard comes by and sees a private server that will eventually become live WoW... they will probably try to shut it down. I would say make the progression in the game so slow that it would take a long time (longer than Blizzards WoW took) per content release.