One thing I can say for sure, is there are better ways of item removal than RNG quality upgrade mechanics. Even if it is just wear and tear requiring skilled crafters to fix things (rather than a tiny bit of coin to an NPC) it works. In fact, it gives craft focused people another skillset that is in demand, and usually needs less resources for their goals. Fixing can still eventually leave items with very low maximum durability in such a system, which means after a while a new one is still needed. However, RNG upgrade stuff is not only rather annoying, but leaves people feeling like they have to gamble repeatedly until they 'win' to even compete. Which in reality means most people don't bother.
Solo players will want the loot, but mining will likely be something that is a group activity on any world with PvP at all. I'm expecting that they will have a variety of other activities that would be viable for trade to obtain such goods from a town.
I'm hoping currency will be local, although hopefully not over-bearing to carry for trade. Maybe there will be some sort of bank note system, where only specific people can cash at towns with a bank building? It would be a reasonable safeguard to see from Humans, although the other worlds might not have any such thing. Of course, there might also then be some black market for such things in particularly evil places...
I believe they mean player structures with invulnerability will be limited to an area around their chosen home, and only one such home allowed (maybe one out and about, but as many homes in towns as towns that are willing to assign you a home). Maybe I'm wrong though. It does make sense to limit personal spots like that, and it is effective at keeping the clutter down. As to maintenance, that's why carpenter NPC contracts exist. There is a sort of gold sink there, although how many might be needed, and how much they cost, is yet to really be seen (1 might only be able to manage a pretty small house, for example, leaving people wanting more if they want more cool stuff).
I'm expecting NPC vendors to sell some things, maybe in limited amounts at random off a table of goods. More important will likely be hirelings. For example, we know about guards and carpenters already. I'm expecting they may expand upon that idea.