What I think Blizzard should do, regarding legacy servers.
Announce two new "Progression" realms (one or more, depending on expected load). These servers should be segregated from the rest of the content on an account - no shared pets, mounts, heirlooms, cross-realm mail, or other unlocks. All toons are starting from scratch.
One of these realms will be Serious Progression, with all the modern conveniences of life removed. No more group/dungeon finder, dungeon journals, etc. The other will be Casual Progression, with those conveniences. Anyone who wants to relive the past can choose their level of comfort. Trying to work through a dungeon tier in 1/3 the time people actually got is enough pressure, I'd think.
Both of these realms will launch on the same date (for our example, Jan 1), containing only WoW 1.0 world data (zones + dungeons, so up to BRD/MC). After launch, the server will roll through one PvE content patch every month. Patches with just world bosses or non-dungeon events will be rolled into the