Well, I'm not going to bother you all too much. Facts side heavily with the theory (scientific-type theory, not crackpot-type, as was mentioned before) that the Dwemer tried to put their souls into this thing, and they can't come back. It makes perfect sense given everything, so why not, instead of stubbornly shouting "no" at it in the hopes it will change, try to perfect it? Or refute it using fact.
Let's try both.
First, in the case for absorbicide (really don't like how that sounds; suicide is killing the self, absorbicide is killing absorption, no?):
The Last Dwarf would talk, if they would let him.
Obviously anything I could offer for this would be mere conjecture, but I'd like to invite everyone to speculate on who the "they" is referring to. The sentences preceding it just list other people who witnessed the Dragon Break, so I doubt it means them. Divayth Fyr seems intent on helping Yagrum remember, so it probably isn't him. This would leave one obvious, but seemingly impossible answer.
You did it again with Big Walker, not once, but twice! Once at Rimmen, which we'll never learn to live with. The second time it was in Daggerfall, or was it Sentinel, or was it Wayrest, or was it in all three places at once? Get me, Cyrodiil? When will you wake up and realize what really happened to the Dwarves??€?
This seems to imply that the Dwarves are not extinct. Perhaps I'm putting too much importance on the 'really' of the last sentence and my interpretation. Also note that every other time 'Big Walker' has been used 'successfully,' a Dragon Break took place. Of course, the Dwemer had quite a different purpose, but many believe one happened at Red Mountain then, maybe implying that the plan went as expected.
You wonder where the Dwemer have gone? Perhaps better to wonder why one remains.
So if the original plan was to bring all the King's horses and all the King's men to put the Dwemer together again, making from their collective souls a god from which they believed (presumably) they were descended, and this did in fact take place without a hitch, what's the deal with Yagrum? In Divayth Fyr's words:
Yagrum, on the other hand, seems to have regained much in the past. He still shows signs of corprus, but his memory seems to slowly be coming back from time to time. He spends quite a bit of time on his own now and wishes to remain alone. I am sure that glimpses of his past, coming freshly back to him, give him much to ponder over. I feel for my old friend. I only wish there was more I could do. A temper seems to rattle him every now and then and I have instructed my sister-wives to leave him be. In time, he will come to and understand what fate holds for him. [emphasis mine]
Well, maybe along with a flood of other things, he's remembering why he was the only Dwemer in an outer realm that was immune from the effects of this giant robot. I don't doubt that some other Dwemer were in outer realms, but they disappeared. Perhaps a special one was created, so that he could 'turn on the robot,' an idea that's come up in this very thread. I guess you'd need the tools to activate the thing, though. Fyr goes on to say:
And interesting thing.... Yagrum confronted me after my arrival from the council, and wished to know if I still had the Tools in my possession. Upon hearing that the Hortator had taken leave and carried the items off with him, Yagrum seemed quite upset.
Now, this is just me, but it seems like an awful load of coincidence that Yagrum was left behind, presumably to turn the thing on, and then upon remembering things, STILL wants the tools. Maybe to study them, but maybe, just maybe, he remembers what really happened to the Dwarves, and they/it are waiting for him to act. Vivec wouldn't sense many Dwemer, because there is nothing akin to Dwemer left in the world; they're something else. Baladas Demnevanni described them as hiding behind math. That might not be far from the truth. Maybe beyond math is more like it.
Also consider that Dagoth Ur, after this went down, who was supposedly the smartest of all of them, and knew what the Dwemer were doing, was adamant about destroying the tools. He wasn't tempted by godhood even a little, until the Tribunal made away with them and he connected to the heart by himself. He didn't need the tools for his divinity, and he wanted them still. Maybe, even in Morrowind (the game), he was acting for good, trying to prevent for once and for all the Dwemer's plans.
I have some questions, though. Say the above fits. I know much is not based in fact, but is filling in some gaps. Now, if Yagrum did whatever the hell he was originally meant to do, what would even happen? Could the Dwemer oversoul have persisted despite Anumidum being destroyed and rebuilt a few times? Wouldn't it take all of Tamriel's souls together to re-make the Dawn? To me, the Dwemer can never come back, because the Nerevarine left with the tools. Even if Yagrum got them, he would just become part of whatever the rest of the Dwemer are.
Word Merchant: Your Landfall theory... If indeed all of Nirn's souls are needed to re-create the Dawn, and the Dwemer did eventually succeed, then it would make sense that other cultures could become advanced enough to try the same, albeit using other means. Landfall would be the rest of Nirn's failed attempt (so still no Dwemer, since they did it the right way, and are yet further down the line). Success would put everyone in the original place, putting an I in the Tower, that is literally ALL WE. Correct?
This is far out there, but if the Dwemer imitate an act meant to achieve the Godhead, and they did it with only a race instead of all races, isn't that still mythopoeia that would grant them at least a taste? It is immitating an act which has not yet happened, or is reversing an act, so..? Questions abound.
And now for a boring refutation of this whole thread.
To the Dwemer and Oblivion belong this treasure and they are there dead.
Each of the aspects of the ALMSIVI then rose up together, combining as one, and showed the world the sixth path. Ayem took from the star its fire, Seht took from it its mystery, and Vehk took from it its feet, which had been constructed before the gift of Molag Bal and destroyed in the manner of truth: by a great hammering. When the soul of the Dwemer could walk no more, they were removed from this world.
The Tribunal used the heart to change history, so now everyone is living in a world where the Dwemer really were killed by the Tribunal. So, they're not alive.
In fact...
Dwemeri high priest Kagrenac then revealed that which he had built in the image of Vivec. It was a walking star, which burnt the armies of the Triune and destroyed the heartland of Veloth, creating the Inner Sea.
...it wasn't even meant to achieve anything other than destruction in the current timeline.
Obviously I don't like this view, and I personally think the two timelines merged, meaning they are both a little true.
So there you have it.
Either:
a ) The Dwemer tried to join their souls together, failed, and are dead/don't exist.
b ) The Dwemer succeeded, and aren't the Dwemer anymore because they're the robot, or in the robot, whatever, and waiting to be 'turned on'. If only we can get another Nord/Orc/Dunmer/? four-way going, the Dwemer might get turned on. Imagine Anumidum's 'muatra,' and shudder.
c ) They got the **** kicked out of them by Almsivi, who were always gods. They're dead.
No matter how you look at it, they can't come back in a future game, unless that future game involves concentrating superhard on a magic-eye until you see an 'I' and become the Godhead. That game would svck harder than Azura at a trial. <----See what I did there?