It's not that which has changed. There will be some increase of goods entering Andor, and this doesn't touch Andor's exports.

But one of the stated reasons why Andor is so prosperous is that part of most nations's trade transits through Andor. The nation is central, and controls many trade routes. Trade from Katar and Bandar Eban transits through Andor to reach TV and Cairhien (perhaps even Murandy). Some of the trade from Saldaea to the south and Illian to the North transits through Andor on that river on which is Whitebridge. A great deal of trade out of FM or Lugard to the West or North transits via Andor. All goods entering Andor from abroad are taxed, not to mention the profits all the towns and cities derive from the presence of so many traders in transit. Four Kings lives on that, for instance.

The SF enclave in Andor will make Andor lose a great deal of those taxes derived from being a central nation controlling so many trade routes. Merchants won't have to transit through Andor anymore unless they come to sell or buy in Andor, and those who won't come with caravans anymore when they don't. They'll have their business agents/buyers go to the SF enclave, conduct their business, and all the rest will be done via Gateways. No more taxes for Andor on a caravan of Arafellin gems in transit to be sold in Lugard, Tear, Illian, no more taxes collected at Whitebridge on ice peppers on their way to Illian. Illianer merchants will go to the enclave there, sell olive oil for ice peppers.

Andor would lose most of its economic advantages derived from being the nation controlling the most trade routes. It has too many exportations to be crushed by this, but the Crown will still have lost what was a very lucrative source of revenue from trade routes.

Other nations stand to lose far more than Andor. The two nations for which this is more problematic are Murandy and Far Madding. Neither is such a big exporter (and competing with Lugard's best industry is another business scheme Elayne has invested into recently...), they thrive on trade transiting through their nation, especially Far Madding which was pretty much a trade enclave specialized in brokering deals between agents and organizing transit, and which once Traveling-based trade is ongoing will lose that speciality. Why bother having your agent in Far Madding broker a deal with the agent of an Arafellin trader when you can go the SF enclave to broker the deal, saving tons on transportation, security, and taxes derived from transiting through so many cities (as cities too often have a levy on goods entering it...) to reach your market.

It's where it was going, but it's doubtful it gets there. Egwene will see the peril this places the WT in if the SF start trading OP services as they did for Elayne, using it for trade. Already Elayne is following the trend and will now offer healing, and it's only a matter of time before she realizes the benefits the Kin and the Crown can make by offering OP services for a fee. It won't escape the Kin's attention very long, don't forget most of those women are also traders...

If Egwene does nothing, the sisters will soon pay the price of their reputation of meddlers, schemers and for their aloofness. People who reluctantly sought the Tower's help will go to the SF or Kin. At least they'll know what the price will really be! Rulers will become more concerned with their relations with SF than caring about the WT. The WT is pissed? So what? The SF can provide the same services without the meddling.

The whole thing about Elayne and the SF beginning to see channeling as a commodity is IMO a plot device to return the AS to a philosophy of service, and also a device for a global ethical system and rule to re emerge, including rules about for trade, and for what is fair game for trade and what the channelers all agree have to stay free, and now available. No doubt a very great deal of OP commodities were traded in the AOL too (it was a capitalist system), everything that's luxury, but very likely all the basic stuff was not only free but also offered universally and fairly by the Guild. A balance between the extremes of the WO's/old Kin's ways and the SF's ways.