Classic + should be entierly new thing seperate from Classic or BFA/retail.
Just start again from after WC3 with new writers and more open factions/allegiances(like aldor and scryer as alot harm to story and game has directly or indirectly come from having the strict 2factions Like nelfs being defanged and never really having fit in Alliance and not fitting for horde really either,same for forsaken not really fitting in either faction).
Take good elements/ideas from classic and all expansions .
And just have same world but some things changed (like faction system is different) and more explination for stuff and characters saved from being wasted(from classic or later(like kaelthas,zuljin,rastakhan,vashj etc).
(and like why we attacked the desert trolls when they werent ever really bothering anyone,or drakari in wrath even though we were fighting same threat in the scourge?)
World is then aslo free from all retcons from last 15years(that have been happening more and more).
Could expand and fix the world,Start with more and different races that were part of factions there at time(like wildhammers for example or ogres).
And with factions not being as strict and having more then horde and alliance,could have evryone play together for pve,but still have the hostilities and skirmishes for PvP but its more for certain races then entire faction themed.
Like could work for/aid the Darkhorde with rendblackhand or Help the dark iron and try get them with alliance or so as dwarf/wildhammer.
or choose to ally with the Scarlet crusade and have different items or cosmetics from them.
Or could choose to side with forsaken against the scarlet crusade.
Aslo have more class +race focus. as in lore classes arent same for all races which could be reflected with different spellnames/visuals(or both) but gameplay is same.
Expanded Tree with more Choices(like fewer but stronger demons or more but weaker,upgrading specefic demon for warlocks) with less 1% this and 1% that(they have their place such style but shouldnt be to many either ) and have more bigger gameplay effects.
And it could aslo just fix some of classes biggest issues from Classic since takes elements/parts from all expansions for the classes and specs.
And it would aslo avoid masssive powercreep that resulted in the squishes that dint fix anything ,and the lore powercreep aswell where we beat a fcking titan.
And removes worst parts of lore like 1legion accros all realities/dimensions(how does that even work with archimonde and kiljeaden?)
Classic + with best parts from classic through to BFA/whatever comes after with new writers would be good,but shouldnt replace classic or any possible other legacy expansion servers Nor Should Replace Current. Should be something different from Any of them.