And this, I think, perfectly summarizes why 'Setting a Standard' is a bad thing, both in design and in evaluation. It encourages an approach in which the first thing you say is 'It has to at least do This'. But HOW 'This' is done is far more important than the outcome.
In keeping with the Witcher, look at the characters. The ones who have any sort of development fall into 2 categories. Either they are old associates of Geralt, or specifically tied to his quest to find Ciri. Their 'Character' has no presence beyond a set-Characters set-mission. Sure, they are well acted and interesting within the story in which they are involved, but if you take away that story, what are they? How would that model function without Geralt as a fixed feature? It's a great system for a set-protagonist, focused story dynamic, but is a disaster in an open ended, system like TES. Being more like The Witcher III would be just reinforcing the core complaints from the last 2 TES games and making them the focus (more rigid character identity, more likearity, less customization).
There ARE some elements of Wild Hunt which could be useful. But there are also elements of Call of Duty which could be useful. That doesn't mean that CoD is now a Standard for RPG mechanics.
If I had to guess, because it's illegal. Just like a bank can't print it's own money, it's unlikely that any organization or Province in Tamriel can mint their own currency without some kind of restriction.
We don't really have any information on the basis of Tamriel's economics, but based on the standard currecnty, and the seemingly arbitrary value of raw Gold, it's unlikely that a Septim is based on or backed by Gold. If there was a resource I would pin it on, it would be Magicka, but that's too abstract to really work into mundane transactions...
I do really think that a simulated economy is necessary, however... But I am not sure that we need quite that much complexity, at least not right off the bat. Simply adapting the Resource and Trade models that 4x games have used for 20 years is a simplier answer and probably better for testing the waters. I do like the idea of merchants having variable gold, though...maybe just having a range that it resets within would be a easier approach to start with.