Gameplay does not translate to lore: the Falmer have good aim because Skyrim does not have more than one tactical AI for NPCs, and because the Falmer wouldn't be an entertaining enemy if they missed most of their shots and swings. If gameplay were lore, then common roadside bandits across Skyrim and Cyrodiil would be walking around in full ebony armor and would be better fighters than most of the Imperial Legion.

First of all, whether or not they are the most powerful enemies in the game is a matter for debate, and they probably couldn't wage war against dragons. You are correct about them seeking vengeance, although it is just against the "surface world" as the loading screen will confirm, and their extraordinary sense of smell would divert them from any confusion. As for their positioning, it is stated that the Dwemer were mostly based in Skyrim, Morrowind, and Hammerfell, but other groups could have branched out but it is unlikely that they would have Falmer slaves there because the Snow Elves themselves were only in Skyrim, predating the arrival of the first Nords. There is definitely advancement going on with them, though, as they are beginning to build better armor and according to Enthir their raids are becoming more systematic and sophisticated. Even so, there is not much of a chance for a full out alliance due to a lack of any form of speech and the absence of any leader or at least a dominant male. In short I don't believe there is any imminent Falmer uprising, and would be surprised to hear about one for the next Elder Scrolls game, but I have to admit that would make a great topic for a future game, possibly set in another era or thousands of years in the future, depending on what Bethesda decides to do with the Fourth Era.

I figured those woman Falmer with the staffs where in charge, and not men.

We also only see the caves we can get to, it has been how long since the Dwemer vanished? In that time we have no idea how far they spread out, or if some area's are better off or even smarter. I think they are a huge threat, they wouldn't win, unless something terrible occurred, but the lost of life could be very high, and it could weaken those nations involved depending on how costly a war would be.

I agree that there certainly is a possibility of the Falmer taking over. If they evolved enough.

While they ARE, in fact, blind, their hearing certainly makes up for it. My current character, a Khajiit with a sneak of at least 80 (I cannot check right now) and wearing shoes that muffle movement sound, if I am not sneaking (or sometimes when I am, if I move too fast or get a little too close), but I am walking, even if I am walking slower than usual, the Falmer can still somtimes hear me and attack immediately. You would think that they might sometimes be a little miscalculated with the position of their attack, but they always know right where I am.

This being said, their hearing is impeccable, and it seems better than what a normal blind person's hearing would be. They are good fighters, and, as said in the OP, are some of the best enemies at higher levels.

If they evolved much more, they could certainly take over, if there are, in fact, many, many more that we just haven't seen. Also, there would be no way to prepare for such an attack, as no one knows where these alleged masses of falmer are hidden.

But as 

I agree that it very possible for the falmer to take over all of Skyrim, I also agree that they would not be able to climb the mountains to take over the other nations.

Wow, 130 Messages on this thread already. What have I created?

I've more or less said everything I have to say on the topic. Previous posts are above for anyone that cares to read them: point being, I don't believe the Falmer are capable of very much at all, and many people are mistaking gameplay features for lore.

You, sir, have created one of the best discussions I have ever done on this wiki! I applaud how long you've made this go, but I'm afraid this is the end. Now it's just time for someone to make a conclusion.

There have been aproximately 3700 years since the Dwemer dissapeared.  If they haven't made significant progress since then(which it kinda looks like) it's a stretch to think that they might have a chance to ever revolt and conquer Skyrim. You can take in consideration this: the two alive Snow-Elf might have been over 4000 years old, so those 3700 years would be a fraction of a generation, but that is only achieved with the use of magic, which we know is not as strong as it used to be. So this leaves us with the average lifespan of an Elf/Mer which is 100-200 years., which makes those 3700 years look like a lot to overturn.

So, short to medium term they cannot pose any threath to Skyrim, even with a decent general (a genius general would make a difference, but that is a stretch, especially with them being wary of anyone not coming from their own race). But, after one or two eras pass by and they are still ignored, they can develop into a proper threath to anything living in the outside world.  That would be a lot worse, with their specific hate against their masters evolving in just general rage and bloodlust against anything else. They are a race that has nothing to lose, enveloping the saying: "A man who has nothing to lose is the most dangerous creature that there is." perfectly. 

So yeah, it looks so good from a poetic rise-from-the-ashes kind of way, but it's highly unlikely and mostly wishful thinking from the sources of this lore: a scientist who has studied them forever and a member from within, seeking revenge for it's fallen race.

I doubt this thread is still ongoing, but I believe the Falmer could return to Snow Elves. People tend to forget this is the world of Elder Scrolls where magic and gods exist. Real world knowledge doesnt translate very well into the world of Nirn. I'm sure a good writer can bring them back if they wanted to. Bethesda left the fate of Snow Elves/ Falmer pretty open as if they didnt still might have plans for them. If Bethesda wanted to truly shut the idea down they would have never let Gelebor claim that there might be more conclave Snow Elves out there and that the Falmer are becoming more inteligent. As other stated we dont know what the Dwemer did to them, it could be some sort of magic that degraded the falmer. The dwarves spend thousand of years underground and yet had the regular form of a mer. Maybe the falmer can come back with some divine intervention like Auri-el changing them back or If Gelebor ascends to god hood and brings them back. if not maybe they will evolve to some form of mer with cool glowing patterns like the animals in the forgotten vale.

As for the Falmer being a threat to the Skyrim, I think so. Given more time of course. Falmer are spread all over Skyrim in caves and in Dwemer ruins. Falmer have been fighting automatons for thousands of year and have survived. The falmer might not win in an all out battle, but if they use guerilla warefar its a different story. Most people cant even go to Dwemer ruin becuse of how dangerious it is, even regular caves.All they would have to do is attack and retreat in succession. The Falmer will always have a safe space to turn to.

I know im late to the party but meh. Shimmermist cave is near whiterun and is connected to dwemer ruins. Inside are of course Falmer. Now some gaurds say they have seen creatures around the area, possibly falmer, and they have chitin fence outside of it. Showing at the least they are going to the outside world. Perhaps over the years they will start to emerge from underground ruins and caves then just start to kill people randomly at night. Slowly pushing outwards. Now there has to be some form of Falmer Structure, how else would they have organized a general revolt, domesticated Chaurus, and not be killing each other. Now im not saying they have a government but perhaps a more tribal government the strong leads the rest follow. So perhaps they will become a sotra new threat to Skyrim slowly attacking people and maybe starting camps in the outside world, this could even mean they regain some sight as they go out more and more, very slowly yes but possible. So full scale invasion is unlikely but more of a slow attack on the people of Skyrim possible.