Some ideas I've had over the years may be near the mark or far from it, but I figured I might as well throw the hat in and see what people think.
I've mulled whether a straight value cut to all things would be viewed as beneficial when Ash points out it has no real effect. It would be psychological more than anything, which could still be desirable. I also agree with Karlotta that we have a lot of open routes and a ton of mineables specifically. I wouldn't mind cutting down on them a bit or tying them more closely to RP activity. Say we keep bonuses for mining factions that create the commodity and then provide the major profit bonuses to those factions that would realistically transport the commodities to a RP-appropriate sellpoint (1-2 total per mineable). We've got the tools to (somewhat) limit smuggling commodities in this way as well - say only Junkers or Outcasts can buy Cardi from Malta for the largest profits, and then we can buff the prices for those items because we've restricted the universe of IDs that can reasonably carry them. Maybe even replicate some of the smuggling routes we've tried in events.
We also have a ton of commodities in the game. Probably way too many. They could be removed or we could "price" them out of practicality for profit and push people toward specific routes, types of commodity trading, etc., and provide the strongest profits for them. Something like the shipping faction bonuses on a permanent scale perhaps, but it would have to be looked at closely in comparison to mineables.
Those ideas don't address the money sink issue ultimately, and I'm still at a loss for the best way to do so without relying fully on continuing developer activity. I always try to structure events so they can run themselves, and it would be nice to find a worthwhile money sink that did this as well.
I'll have more thoughts later on equipment prices, but many pieces of equipment are created by players and sold to other players with prices we can't really control. I don't think pulling them from the player market entirely would be beneficial because they are tied with activity somewhat and they provide alternate means of "grinding." Even if we did limit transferability somewhat (and there would be a few ways to do this), I wonder if there are too many in circulation to matter. There have been suggestions about making codenames a factory-produced item. That requires coding work it doesn't seem anyone is willing to look at currently, though. @Haste has suggested using the PVE zones/missions to drop materials that would then be used to make those codes to connect the PVE portion of the game in a better way than cloaks possibly do. I'd love to see it.
Speaking of which, I know some people are heavily invested in farming, but it seems to be particularly spread out. When the first few came out, they concentrated activity heavily (partially because they were new). I'd like to see it go back to 2-3 open at a time based on story development or other places where it would make sense.
I'd personally be fine with someone wiping my cash that I don't use, but it might be a touchy subject to bring some deletion mechanic back. Perhaps instead of deletion characters that aren't logged/used/accessed over a certain period of time have their credits reset but the ship preserved in case someone comes back so the means aren't lost. This seems like one of the more difficult issues to address and will need some serious thought.