There's one problem with your theory: everything is actually hinting that the Soul King planned for Yhwach to stab him, and that the Kamikake was the tool he put in place to make sure Yhwach absorbed his power.
Further more, we know Soul Society isn't telling its shinigami any part of the story - at the very least, the shinigami academy has not taught quincy matters for at least 50 years (because Rukia never learned even the name). Even to Isshin, who must have been the potential captain candidate that Masked databook says was being considered for post during TBTP (therefore appointed at some point just after TBTP), quincies were little more than a rumour of an almost extinct race. He had at least heard of quincies, but it wasn't until he met Masaki that he realised some still existed. It therefore doesn't sound like even his generation was taught much about quincies.
We can also see (as you mention) that, judging by the quincy comments on bankai, the quincies weren't being told the truth about the shinigami either, if they're being told anything at all. Indeed they weren't even being told the truth about the spiritual cosmology of their world.
Further more, both Zommari and Grimmjow's comments during the Arrancar Arc regarding the thousand-year history of the hollows suggests that shinigami (and probably quincies, too) aren't being told the truth about hollows: given that only a few hollows seemed to know what a quincy was, most hollows probably don't know the truth about their history either.
So, there's a huge swathe of information missing from common knowledge regarding the history of the shinigami, quincies and hollows - all three of them.
Note that at the very beginning of the manga, we only heard Urahara's version of the tale - we don't actually know what the shinigami were typically taught because, by the time Rukia's generation came along, the shinigami weren't being taught anything at all. When Urahara told Rukia about the quincies, he actually talked about all quincies left hating shinigami, yet Uryuu was allegedly the last remaining quincy.. immediately raising the question of what Urahara was withholding about the quincies. Just to add to that, we don't know what version Souken told Uryuu (nor did Uryuu ask Ichigo to confirm what version he'd been told), but Souken did tell Uryuu the most important thing was to prevent another massacre - so, just as with Urahara's comment, we have the bizarre discrepancy that there's only supposed to be a single tiny family of quincies left, yet people are talking of preventing another massacre and 'all surviving quincies' hating the shinigami.
So, the very moment the quincies were introduced to the manga we were tossed a giant, gaping question mark about how many quincies really existed, and who knew what about them.
The timeline isn't exact (the time-skip causes problems). However, if we use Chapter 537 as a starting point, to give us -9 years as being Auswahlen, we have as follows:
Note, I'm adding 3 to everything on the grounds that Masaki died 6 years before Chapter 1, but Chapter 537 states it's the ninth anniversary of her death.
0 = Post-Chapter 537. Yhwach has fully regained his power and claims in 9 days he'll regain the world.
-3: Chapter 1
-9: Yhwach regains his intellect, immediately performs Auswahlen to begin the process of regaining his power: Gemischt, Masaki, Katagiri die. Also, this is the year Sado's parents die, too.
-18: Ichigo, Uryuu, Sado and Orihime are born.
-23: Everything but the Rain (Aizen is evil, White is mysterious, Souken is suspiciously absent, Urahara is dodgy, Masaki is hollowfied, Isshin goes AWOL, Ryuuken has a bad day).
-53: Grand Fisher activates, Hisana dies (yes, same year for both of these - given the hints that the Grand Fisher may be connected to Aizen's experiments, is Hisana's death a coincidence?)
-99: Yhwach regains his heartbeat, immediately begins the process of regaining his intellect.
-104: Turn Back the Pendulum ends (Urahara banished, Visoreds created & banished).
-113: Turn Back the Pendulum begins (Hikifune promoted to Royal Guard, Urahara promoted to captain, Mayuri released from Maggot's Nest, Research Institute set up).
-114: Gin joins the Shinigami Academy.
-115: Rose becomes captain.
-203: Second Quincy Massacre; also the point where a great fluctuation in captain turnover begins (only Yamamoto, Unohana, Kyouraku and Ukitake predate this as captains).
-999: Yhwach is sealed and begins the process of regaining his heartbeat.
-1000: the Blood War begins: Quincies allegedly begin, Gotei 13 begins, Hollows in their modern format begin. Soul King hinted to have begun. First Quincy massacre occurs.
-2000: the Yamamoto/Choujirou bromance begins.
-2100 (approximately only as Renji's graduation date is a plot hole): Shinigami Academy (as we know it) set up by Yamamoto.
To note a few things:
TBTP lasts 9 years - that's one of Yhwach's numbers.
Yhwach regains his heartbeat 5 years after the end of TBTP - nice Quincy number right there.
Hikifune is promoted to the Royal Guard 14 years before Yhwach regains his heartbeat (1+4=5).
The Quincy Massacre is 104 years before Yhwach regains his heartbeat (1+4=5).
Time-skip adjusted, TBTP ends 104 years ago (1+4=5) and begins 113 years ago (1+1+3=5).
There's 797 years between the two quincy massacres (7+9+7=23; 2+3=5)
Edited by Milareppa, 29 April 2015 - 05:52 PM.