While I never found a coherent new thread after the http://www.gamesas.com/topic/1451586-summing-up-the-amaranth/?hl=%20summing%20%20up decided not to continue, I just feel like adding a couple of notes and showing you guys might already presume too much. My only sources will be the IRC logs on the Anu = Amaranth relevation (spoiler of the opening post in the above-linked thread), http://www.imperial-library.info/content/childrens-anuad, the http://www.imperial-library.info/content/loveletter-fifth-era-true-purpose-tamriel, and the discussion I've seen so far around the forums (basically only the Summing-up topic above).
I failed to see what's so hard to grasp on the new-dreamer-takes-over concept. The Godhead originally dreamed Anu, Padomay and Nir. There was this major enantiomorphic event, but Nir had already given birth to Creation before Anu ever went to sleep. That means there was something already. As to how could Anu go to sleep in the sun that shouldn't have existed yet, I can think of a few options.
a. a contradiction in Anuad, or not everything is linear there.
b. Aetherius already existed as a part of Creation. I doubt Anu needs a hole to go through from Void to Aetherius; I think he could move into "the sun" as he wishes, seeing as the primal forces can somewhat do that even with Time. Maybe he actually created "the sun" (i.e. Aetherius?)?
c. your Magnus-shot-himself-into-Anu theory has some ground and boy will this give a headache.
d. "The interplay of Light and Darkness", according to Anuad, created Nir. So Anu was the Light, the sun, all along? He curled up into himself, basically?
Anyhow, I'm sure you've dreamed of the world even if you didn't originally create it. About some everyday stuff. There can be a table in your dream. There can be you in your dream. MK also brought up these points. Anu's only perceptions ever were of the empty world he was living in at the time of creation that Godhead dreamed. Where could he have started to dream of if not of those same few things that were around? I mean, our dreams can be very detailed - the gravity is okay, the colors are okay, heck, even things can be on their actual places, we see the faces of the people we know in detail, etc. Anu, not having that much of anything in his "world view", of course dreams the "world" as he's used to seeing it, at start.
My two cents are that
a. this is the starting point of his dream from which he's yet to awaken. That Padomay really died, but he dreamed him still being alive and coming back for revenge, and all the rest.
So his dream made all this happen, and everything after it. He dreamed of himself awakening and the Dream has continued from there. But, maybe he's about to awake for real. Remember that
. Maybe he has already awakened, even. There can very likely be a phase in the Dream that is without a Dreamer at all. That is, between Anu and the next Amaranth.
(Vehk from the Loveletter is acting like some future ambassador to love, for avoiding the Landfall. Vehk loves all, for they are him, and he loves himself, and vice versa, so he feels that he could take over the Dream [OR, start over a completely new one]. On the other hand he might encourage the love for Anu to continue, so that Anu could sleep more peacefully again. But aren't these, for a CHIMster, the same thing anyway?
I'm pretty sure the ending of the Dream will cause Landfall - the Dream, after all, is beginning to know. Landfall smells like a consequence of the Dream "knowing [it is just a dream]", or "no longer needing a dreamer", and Vivec acts as a savior / bringer-back of the old balance / most likely the New Dreamer, seeing how different the Fifth Era seems according to the Loveletter.
Maybe the crumbling of the Towers already are signs of Anu slowly awakening. Maybe he is just not satisfied enough about his Dream to remain asleep anymore. Here's me, anyway, thinking that the Towers link to Landfall and stuff, even though Landfall might be anything. I just see them all - Thalmor, Towers and Stones fading, Landfall - linking together and possibly marking the end of the [current] Dream [and possibly the beginning of a new one]. "There is the next Amaranth."
Remember also that The Thalmor will win in the end, whatever that means.
b. It is possible that Anu truly awoke when he woke in the Anuad. His relatively short Dream (only "many ages" long) was enough to put forth creation and make the life spring, and then he could have acted the rest awake. We would be living a long, long period without anyone dreaming at all, the Dream just doing what it wants. OR, it has been the Godhead ruling it once again. Even if this theory is very unlikely, still, what was that presupposition about Anu "kicking the Godhead awake" and stealing his Dream, and Godhead being reduced to some insignificant thing from the past, the kick-starter and nothing more? He might still dream, for all we know, or he might still be otherwise significant. Even if Anu is still asleep (which I believe in - after all, he also "IS the the Amaranth"), the Godhead might Dream next to him, and/or together with him. Don't forget the Godhead; no-one confirms he's awake. Again, I think it's only Anu dreaming, but don't presume too much about the Godhead! We don't know him. OR, Anu kind of mantled Godhead and became him..? Did the Walking Ways already exist, are they some kind of universal forces in the Dream that could also be used by the Dreamer(s)?
By the way, who says there are only two Amaranths? This is something I also seem to be reading between the lines. We are "only" looking for the next according to MK, which implies there may be even more coming in the distant future. Or, maybe they could Dream simultaneously as already rambled above.
Anu "takes over", or something alike, the Godhead's Dream. It happens with ease, since what is in the original Dream are all that Anu has ever perceived. Notice how realistic dreams are even in our world where there is arbitrary amounts more to perceive than in an empty Void.
So once more in a nutshell:
Anu dreams still to this day. He's either waking up or already awoken, as the instability of Mundus is seemingly increasing game after game. We might be nearing - or already living - the period between the Dreamers, where no-one Dreams. After all, MK said that the "Dream is starting to know longer need a Dreamer". This could relate to the Thalmor, the Towers and Stones fading, and the Landfall. Vehk might be the new Amaranth in already having achieved the CHIM, and thinking that only love - which Anu was left without in Godhead's dream - makes the Dream worth continue. He might also be trying to take a new shot at becoming the Amaranth himself. Seeing how different the Fifth Era is, he might succeed in it and start a completely new Dream (or Dream-within-a-Dream, though I take it's the first option). Godhead might still have a significant role in all this - he's not necessarily been "kicked awake" and reduced to nothingness. We could also have more Amaranths other than Anu and the next one (be it Vehk or not), since right now we're only looking for "the next" one, not "the final one", for example.