I’ve wondered this for awhile, We have faction and race changing, which are honestly more drastic changes to a character, but not class?
It would be really useful for those of us who are very attached to our one character 
Personally I would be most interested in this for a chance to play through the other legion class halls and the DK and DH intro’s
I can’t say I’m totally sure how this could impact other playstyles, curious to hear other thoughts!
I can’t see this ever happening.
The issue of gear alone is enough to shut this down completely.
I don’t understand why one couldn’t just make a second character; I am also very attached to my main, but the knowledge that I am missing out on race/faction/class specific content is enough of a driving force to make me experience what I’d otherwise miss out on.
Blizzard is definitely not the thing in the way of you not experiencing that content; it would be near impossible for this to be implemented. Just the amount of spaghetti they’d have to untangle would be way, way too much to even consider. I don’t particularly like boosts, but if you want to, you could absolutely be [main’s name with a one letter difference] the boosted [class you want to play] with the same race/customization options/etc and you’d be really close!
They could implement something similar to the “job” concept from FFXIV, but that would fundamentally change the entire philosophy of the game, progression, etc. Your class is inherently tied to your character, and I think it should stay that way. The only two classes that are muddled to me is paladins and (holy/disc) priests. I could buy a priest turning into a paladin or the other way around, sure, but a warlock becoming a paladin? That would break lore and break the game, unfortunately.
This wouldn’t work because not every race can be every class and if this service were to actually be a thing, it would have to be prohibitively expensive because you are essentially switching to a flavor of the month class and buying two services in one.
You would have to factor in the max level boost which is $60 and include a race change which is $25. So to have paid class change it would have to be at least $80 but that would only account for the level 60 boost not level 70, which does not exist.
It is much more feasible to just reroll another class from start and if you really interested in just doing the class, you can do an allied race. Plenty of ways to level pretty quickly.
No thanks from me, I’m sorry. Unlike a certain other game, it would not function as well in WoW.
And as soon as some say “class change service” one thinks all the complications. I had a long post that ended up in word-salad ranting. Chose to delete it because well, just ends up with ranting.
I just see it as one big problem which can be solved easier just by rolling a new character. You have so many points to take into account.
hmmm Okay interesting thoughts the structure I was picturing would be similar to race change, about 25$,
-Choice is restricted to classes available to your current character race
-Character would be sent to faction capital (except DH, DK and Evoker)
-Currently equipped items would be mailed back to you
-Class titles would not be lost but would not be able to be active while not the right class
-Class mounts wouldn’t be lost, since they are account wide
-You would retain your character’s current level
-Temporary lockout from current content heroic and mythic raids
-Active quests (in log) cleared to prevent whacky situations
As someone who has played with the same character for 18 years now (so yeah, you can say I’m a little bit attached), this would be open a box of worms that I don’t think the game’s old code can deal with. I would take multiple expansions worth of changes to make it even close to viable in WoW.
I think it’s fine not to have every quest completion in the game on one character. I have done it to complete all Legion Order Hall mounts.
I don’t think it’s a good idea. One of the great things about leveling up in a class is learning to play as you go. The whole reason you don’t get all your spells at level one is because you’re learning the basic rotations and mechanics of the class. You get new abilities slowly so that you learn organically.
Some classes are just flat-out easier to play than others. This mechanic would be exploited by people leveling up easier to play classes and then switching to more difficult classes and not having a clue what they’re doing. It would be a nightmare for dungeons and raids.
Seems like this is basically covered in buying a boost. You just have to end up working for some stuff that your main already has is all.
Probably it would be really difficult to implement.
But do we really want it? If you have been playing one class for long time, you suddenly loose all your gear and transmogs.
What would be the benefit of class change:
I think classes in WOW have much deeper connections with the lore compared to other MMOs. In other MMOs it’s just your character’s job. In WOW it’s your character’s origin, identity and future.