So there are around one thousand seers, but only five of them have used magic? That seems a bit strange. The next very important question is how many non-seer wizards there currently are.

It's very difficult to get any sense of how prevalent magic actually is in the EGS universe, since all examples come from the extremely stilted Moperville case. Moperville's population is probably around 50-75k based on it having two high schools. How many awakened individuals would it actually have under normal circumstances? Raven and Noah are special cases who just happen to be living there and most of the core cast got access to their powers through unusual inducements. I count Mr. Verres, Greg (he qualifies as awakened right? Just with martial arts magic or something), and I guess Nanase (who it seems like would have awakened eventually regardless). So...low end estimate, wizards are about 1 in 25000. That would put the global wizard population at somewhere between 250 and 300 thousand. Apparently the magic police are better at their jobs than it would appear given their actions in the comics (or, to shake the grimdark tree, in places like China they just kill all the wizards).

If that's true, then a severe change would still have a very substantial effect on the presence of magic in the world, since it would reduce it's prevalence by over two orders of magnitude. But it's true it wouldn't last long.

Then again, revealing the presence of magic in a world with hundreds of thousands of wizards...ugh.