The problem with old-school is that it would only be fun for a little while, then after that we would need to actually solve some problems and if we're going to need that then old-school is kind of a waste of time, in that it wouldn't really fix anything, but at the same time I personally did enjoy old-school far more than the clean, smooth, easy and boring game we have today. TBH bugs, scammers, other rule breakers, random disconnects, all the "roughness" of the old game made it so much more interesting. But I don't suppose that you intend to bring back any of those things.
The old graphics would be nice to have (although any update that would change them would risk upsetting people), but I think that the focus should be on the economy, as the current economy is designed to depend on PVP and that's simply not working. The reason I think economy is so important is because it's what makes the game feel rewarding. Currently we have an oversupply of items, that means that when players get an item from anywhere, then they get something that there's already too much of in the game, that doesn't feel rewarding. If there was not an oversupply of items but instead a demand for items that exceeds the supply, then getting an item that there's a demand for would feel rewarding because the person achieved something that they would feel needed to be achieved. So for that reason, I don't think that the economy should be judged solely based on how many items are traded, as that doesn't really say much about the state of the economy. People are often handing out items and those people sell it to other people, who collect those items, because they're bored. That's not a sign that we have an active economy, because an inactive economy causes people to collect items simply because they're bored and those people collecting items would make it seem like the economy is active when one only looks at the statistics of how many items are traded.
I've seen four solutions that have been proposed that would improve the economy:
1. A server reset. That's the worst option because it doesn't actually fix anything, just temporarily hides the problem.
Some other things that are not helpful when it comes to this problem:
Reducing drop rates. Because the problem is lack of demand for the items, oversupply is simply the symptom that we can see, not the main issue, reducing drop rates only means that people need to grind more while still not getting anything rewarding for it.
Adding new items. This is a temporary solution that hides the problem as in the beginning there will be a demand for the new item by people who want to check it out, but after some of those new items are in the market, the new content will be just as boring.
I'm not saying that those things can't be done for other reasons like for balancing reasons or simply to add more content to the game, but they aren't long term solutions for the economy.
2. Make items degradable and unrepairable. This sounds like a joke but it would be the most efficient solution, with the downside being that it would be a problem when it comes to trading.
3. Make the game far more dangerous, by boosting all NPCs' max hits a little bit and boosting their accuracy by a lot and when PVMing actually starts causing mild cases of death then change the death mechanics to make it so that when people die then they actually lose items. The problem with this is that some content may become too difficult and may not be worth it, but at the same time balancing it would likely only require adjusting the values of a few variables and as such probably wouldn't be too bad, whereas getting decent feedback may be an issue, as most people would ask for the game to be made easier, even if the game is already way too easy and they themselves would enjoy the game less if it was actually easier.
4. Convert items into cash. This may be the safest option to try. The idea I've seen recommended is that a high-ranking staff members should buy out items from the market and create a one-time decrease in item supply. That's a temporary solution so I'd suggest that if that's what we want to do then we should increase high alch values of everything except consumables by a lot. The high alch price would create a minimum price for all of those items. People who can't sell their items above the high alch price would be sinking those items by alching them. This idea would eventually require cash sinks to be implemented, which should be really easy, I'm sure people could come up with lots of different ways to sink coins, so I wouldn't worry about that now.
The problem is that all of those high alch prices would need to be adjusted manually as even increasing all high alch values by say 10 times would make some items give too much money when alched while other items that we have an oversupply of would not be affected in any way as the high alch price may still remain way under the market price.