I am really worried about giving players that are sitting on hundreds of millions of gold if not more than 1 billion the access to a market with 100.000s of customers with the same convenience as for a server by now.
Currently it’s already a battle of buying out current high value markets and dictating the price with reset battles (or auction reset bots/scripts, had my XP with that in early SL and reported those). Maybe a larger influx can (!) compensate and throttle the impact of a few but once it shifts towards very few players controlling a market I don’t see an economy that is lucrative for the individual player/crafter.
In addition:
Since restricting auction posting numbers is a bit risky, increasing the auction deposit fee is another way to deter players from reset-spamming the same auction over and over. Tying it to the intended price and maybe having way less return on cancelled auctions could be a posibility. Especially stuff with a really low deposit value (long term enchants only ever cost 1s to post, it was a reset fiesta for years) finally has to reflect the profit players intend to make.