I don't really know if it really has chanced that much as far as like a 5 year time frame goes.
There was a pretty small flea market near my place I'd say up until 2 years ago before it closed down.
The thing was while there were only like 60 vendors I seemed to be the only one looking for games
so I scored expensive ps1 ps2 titles gamecube etc for pennies regularly. Even business vendors had great deals it was pretty small so for the competition it wasn't worth it to come there traveling costs etc. I could come late and nothing would happen deals where there this was just 2 years ago.
While in bigger flea markets you have to be lucky that someone unpacks stuff. I've scored boxes full of snes stuff and rarities for cd systems on flea markets and that wasn't to long ago. I don't go to flea markets that often though unless there big. However when scoring stuff I was or early the first one to arrive or someone was unpacking thus being the first to see the items.
I don't think the state of these kinds of things chance in just a couple of years the thing is when there is allot of competition the stuff will probably be gone I might even say hours before the market officially opens when it isn't a super big one not to mention that even when your early you have to compete with many others.
you have to imagine that while walking on the market there might be dozens of other people in different spots that you haven't passed yet even in the early stages, whether they like the hobby or want to have a quick flip, many people are looking and if your not first someobody else might have beaten you, especially when there is allot of competition and your not first there is almost no chance of finding good stuff since there are allot of people who go to every stall when people are unpacking there stuff, the reason why I don't go to flea markets that often. those antique resellers are crazy
While stuff on flea markets will most definitely decrease when the years go by and ps3 ps4 wiiu etc will replace those empty holes. the thing that impacts these dry flea markets the most are the amount of fanatic people looking for stuff, especially the early ones who help people unpack there stuff. I actually think that there are some people who go to the markets many hours before the opening time.
Things don't chance in just a few years, the deals are out there and while it slightly decreases every year it is simply due to that many people are looking, you cannot be at all places at once so naturally for many people the deals will be slim. If you have places with less competition deals are pretty easy to get but in competitive areas unless your pretty hardcore you will be just one of the many people who picked up a mediocre deal here or there in other words It's not worth it to go to the flea market.
If you score something nice at a flea market you where probably the first to notice it usually when it was just unpacked if not it means the competition is low to non existant.
not to mention that in a pretty big yearly flea market in my country just two months ago I've seen other people score big also retro stuff for cheap and those are just collectors, I can't imagine what resellers scored people who do this for a living thus needing to have the drive to find deals. The early bird gets the worm while the others are left with the leftovers It's just how it works a few get the deals while the others barely get anything. deals are out there but the competition is fierce retro game collectors and resellers alike.
Just remember smart phones have already been here for years It's not going to chance that much in that departement, there are just to many buyers resellers looking for stuff. If everything has been looked through before you have been there it's only natural that deals will suck.