Trying to add some suggestions or ideas that would also be new content / style of playing:
In Tibia we had an option to choose between two NPC stories, after completing the quests the character would be able to sell items for one of them. This enabled you to farm items that had more value and/or buy from others to sell to these NPCs.
I can think of a similar system in ToS in which we could subscribe to an NPC that fits a specialization. For an example, we could have a character to sell recipes for reasonable prices, other to sell items/recipes based on rarity, other to sell plate armor parts, other to sell weapons.
I can’t really say this would work or not. But surely it will increase silver gain while making us have a way to actually make money in different places AND with different characters, even Tanks or Supports, as we could select another merchant option and transfer items through Team Storage. It would also make us want to increase it to big transfers instead of gears only transfer.
If you really think about it, there’s only one well known place to make silver (not by selling items and not dependent on RNG / bossing) and to make it in a effective way you can only have about one person per channel which means only about 7 characters can farm silver effectively in a given time with great effort for a low amount per hour. This is why I think this would help a bit on the issue while also making people play more and giving more content.