This is an MMO.
The way a lot of the game aspects - gathering and auction houses to name a few - have played out on a lot of medium/low/recommended servers seem to me obviously not intentional, considering the classification of the game. Blues said that they will actively tweak gathering (mining/herbalism, possibly skinning), and yet they are keeping them as they are. This suggests that they believe gathering plays out about the same in each cluster of realms in the cross-realm zone system, and is balanced as they see fit.
You should tread lightly with arguing about this unless you are a wall street economist (whom honestly I bet there's one or two of on MMO-C) or something like that. Blizzard probably (how many big-sallary economists do you think THEY have? a lot) knows more than most people the details behind how anything impacts the economy in the big picture. But this isn't the point.
Now that you understand why CRZ is here to stay, here's my theories and questions to the (much smarter and economically bright) MMO-C community:
Anything you do in the game world that gives you items or gold impacts your server's economy (your auction house).
CRZ impacts the game world, particularilly gathering.
[Scenario] CRZ Cluster X
realm 1 population: 11k
realm 2 population: 7k
realm 3 population: 2k
Since supply is determined by demand, we (based on probability) assume realm 1 gets 55% of the mining nodes, while realm 3 only gets 10%. In the long run.
Okay, this means they will technically get as many ores per player. But this doesn't work for a low pop realm. A low pop realm feels a lot more like a solo-game because the small demand means that all suppliers who are interested in making money will find a part of the market to score monopoly on.
What are the downsides to simply linking the auction houses on realms who are already linked through CRZ?
All CRZ clusters would have ~equal AH. The big realms, who are in a CRZ cluster, would have their AH kept as it is (I know it's painful enough to post auctions as it is now on big realms). Medium realms would have their economies slightly improved, and all the small pop realms would have their economies completely overhauled (in most people's opinions for the better).
I would like to hear other people's opinions on how you could potentially make cross-realm auction houses work.
I agree with that merging servers is a much better option than CRZ and CRAH, but it seems like something Blizzard is hestitant (for whatever reasons) to do.
There are probably some mistakes and misinformation in this thread, and you are welcome to correct them. This was a quickly written baseline theory that I'm hoping can tweak into an idea of how CRAH could and would work.