Here is my opinion on it,
A lot of people will blame stakers dumping gold, that affects short term prices but the gold has to come from somewhere and stakers dumping will not affect long term prices.
Gold is coming in the game at a faster rate than ever
Before zulrah was nerfed, it was like 3.5m an hour I believe or somewhere around there at max efficiency and gear.
Vorkath now, at max efficiency and gear is around 4.5m and consists mainly of alchables.
Revenants also before nerf, were introducing large amounts of gold in the game. They weren't overtuned drop wise for too long of a period so who really knows the effect they had from a macro pov.
Drop tables like those, with the fact that players are getting more powerful, rigour, tbow, DHCB buff, ancestral are leading to faster kills and an increased rate of GP coming in.
Players also have a wealth of information now on how to farm bosses more efficiently.
Gold is coming in the game at a much faster rate than going out. Sames applies to items, especially with current death mechanics.
Just my two cents