There's a lot of plans for the economy, with extensive plans regarding everything from shop management to supply and demand etc.
Saying that though this does open up some interesting ideas and I'll be noting them down to discuss with the other team members working on economy stuff.
My mentality is I only want to have to fix things once. Going back and changing things again and again takes time away from working on other stuff that helps put foundations in place for other aspects.
But for me the other thing is making sure whatever we put in is not just for its own, one use. It should be able to be used in a number of ways, and integrate well with the rest of the game in a way that makes sense but is also enjoyable. For example, a lot of people had ideas about how rails should be implemented, but what we ended putting in made so many different things possible. Similarly a lot of people have ideas on missions or bounties or crew or shops or whatever, and while in the current game it might be a good addition; what we instead have in store goes way further and ultimately makes for a more inclusive, engaging, and fulfilling experience that works in the ever changing environment of StarMade.
In relation to this idea, I can already see ways we could implement it and tie it into other plans for the game. Since most of what this could integrate with is in relation to stuff made aware to the community as a whole through our Development Direction news post, here's what I can picture.
In the current plans there's some new stuff that will change regarding factions, but for now we'll include faction stations as part of the example.
So what I can picture is that faction stations with a shop module and an additional block or two (TBC) will be able to connect to the Frontier Marketplace or whatever we call it. Where you can show what you've got up for sale, or see any requests, similar to the Exchange showcased in the OP. This wouldn't be necessarily managed by the Trading Guild however they would obviously have a big presence. On here you may also see any missions that you could accept, such as taking on board a transport mission to deliver items for a commission. All of this could all be driven by your stances with factions however, so I could imagine for example if your faction is allied with the Scavs (currently pirates) then you'd see what they have up for offer and have transport missions for them, but you won't see what the TG has on offer, because you're diplomatic stance with them is that you and the TG are enemies. While you might not see any information around their trade routes etc you might possibly, while flying around in space, encounter another player currently engaged in a TG transport mission, and so you might then be prompted with the opportunity to accept a pillage mission to attack the transport and acquire what's being transported. However the opposite could happen as well, where someone attacks your own transport that you requested or are currently engaged in transporting.
Similarly the marketplace or exchange or whatever you want to call it could be where you view all the open bounties at the moment, again they could be contextual, i.e. a player or faction might put up a bounty only available to them and their allies, or it could be open to anyone, resulting in perhaps a team mate turning to try and take you down to cash in on the bounty on your head.
Mattering what we want to do and balancing, the marketplace could easily extend to let you place ships that you've built, up for credits, or even a design that you've done that another player might like the blueprint or design of. However this easily gets into exploitation if one player purchases a ship blueprint then puts that same blueprint up for sale to compete with the original players' listing.
Who knows, beyond selling and buying blocks, there might even be a market for creatures or items from creatures; or all manner of other items.
The contextual setup that I have in my mind will restrict access to within a certain proximity to a station or planet that's set up to access the marketplace. That setup works best with our other plans, making the marketplace not an instant access sort of thing, while providing a solution to obviously all the logistical aspects of it.
So as you can see there's a lot of opportunities to expand what is possible. While none of this is confirmed, mere speculation on the idea on my behalf, there's some interesting ideas that can come out of it.