The greatest threat to this status quo is the existence of Dagon, whatever few, if any shoggoths, the Illithid, Thoon, Beholders, any form of alienist and magic, though on priority are Any remnants of the H.Pverse so Shoggoths, the Aboleths (especially there elder) Dagon, the Illithid, Thoon, then lastly beholders, With Alienists bein a tier of their own
Dagon, because his existence is too close to that of the other, and because of his nature as a demon, apothesis into a true demon (Demon who's state of origin is switched/moves to that of the unknown, thus eldritch, change, incomprehnsiblity, and eventual change towards law violation thorugh solitutde similar to an alienist transformation, but it too is not achived through specific, or sometimes even unknown or aware means)
Shoggoths, because they eventually get too smart for their own good, or in most cases gleam the discovery of the great ones via their origins on icy lands.
Aboleths, as they may very well be able to travel between this world and Pathfinder, many hold eldritch knowledge of the dark tapestry and simply put, through geometrics allow for mull bullshit that wants to into yogg-soggy bullshit (always the risk of promoting a backdoor into D&D which the gate may aceess far realm or not)
The illithid, as they exist over a multitude of formats as possible fission spawn of Those lesser versions of Cthulu I can't quite remember the names of, and even operate with existing (thankfuly dwindling) eldritch knowledge of great ones (and hopefuly not) Outer gods, given by their elder brains or whatever knowledge they have left of their once great empire, and of course, their new deity also may reach an intellectual level capable of gleaming geometric usage, theorum, Alienist practice and far realm research to become knowledgable to reach out to that which lies beyond and fuck everyone over.
Thoon, because it may very well be at great one status or of a similar nature.
Beholders may very well be related to Yog-sototh (fission?) apperance betrays the purpose of their form if seen from a greater scale, hold a very similar nature to that of Yog-sototh in the fact that they orbs with eye stalks that outstretch to a multitude of powers, levitate and have relentless seizure attack patterns (yog sothoth has a thing for going danmaku on someone's ass when he's brought forth without reason or to smite bitch if you've watched stuff like that one film he shows up in, and the beholder cousins (eyestalkers or something) belate a similar nature to Yog-sothoth's alleged enjoyment of travel deiscovery etc…
Alienists are on their own because they can be used to ruin everyone's day (Enough of them could unmake the far realm), because they can effectively become Great ones, or at least reach the larval stage to such a position, and because I give them the leniance of how their powers for summoning work, whcih is basiclly where anything they summon is not what they summon but merely a creature residieng in the farm realm suitored to fit the form of what they intend to summon, (So the bigger the form of the intended summon, the more significant a creature is drawn to suitor it.)
This means that in theory, if an Alienist were to SUMMON FUCKING DAGON or at least have any hand in the construction of summoning circles or rituals for greater creatures of the planes, a creature is made to suitor a replacement of these beings, (or worse, make a combination of both).
So what the fucking shit do you summon when you summon a Demon lord or an Archfiend, or Dagon, who already leans on (nearly unknown to all) or that one Demon mother mist thing?
Yeah, whilst it just means Apply pseudonatural template gamewise, I thnk there's a limit to this sort of thing when you consider what the fucking shit happens if you try to summon something that required preparation at least, you won;t just be getting a follower with some perks, if you know what I'm saying, You summon DAGON as an alienist, and you get his far realm equivanlent, and I think that sure as shit makes sense.
I'm also pretty sure it damages the Far gate too, hence the danger Alienists that go the extra mile pose, never mind how fucked shit will get if there's any multiclassing into to Druid (Shubbery Niggerbitch Coon-Young) Oozemaster(YOUR ARMY IS IRRELEVANT, I SHALL FLOOD YOU IN SHOGGOTH TEKILI TEKILI MOTHERFUCKER)