New - Well after the most recent chapter it looks like I can throw most of these out the window for now, well it was fun while it lasted. At least number six is still standing strong and I love how "serious" Isshin is taking his fight with Aizen.
1)Ichigo is revealed as being a Shinigami/Arrancar hybrid. Isshin is the shinigami part and Masaki is the Arrancar part. Wether Masaki was natural or artificially made I don't know but this could lead to how Isshin met her and learnt of the arrancar, but like Nel she was peaceful and a relationship was created between the two. Soul Society would never of let this continue leading to Isshin and Masaki going to the living world in undetectable gigai's supplied by Urahara. Isshin knows how much Masaki meant to Ichigo so thats why he cut off Aizen from revealing this to Ichigo as learning that his mother was a former hollow might be something of another shock.
2)Isshin explains himself to Ichigo (details don't matter in this prediction) before going ahead and matching Aizen blow to blow but gaining nor losing ground, seeing this Ichigo joins in and in perfect sync father and son defeats greatest evil against SS known to date.
3)Isshin explains himself to Ichigo, goes to attack Aizen but like everyone else is eventually overpowered, reveals shikai but gains no advantage and as he is about to be struck down Ichigo defends him while Hollowfied. Now Hollow Ichigo comes in trying to transform into the form we saw fight Ulquiorra, maybe getting halfway through the transformation and injuring Aizen at a rate that the Hogyoku has difficulty healing, but Isshin see's this and steps in saying something that gives Ichigo the resolve to force back his hollow and regain control. Aizen fully healed taunts them more but overuse of the Hogyoku causes him to begin losing control of its power, and using the chance Ichigo and Isshin hit him with a combined attack defeating him and permanently damaging the Hogyoku which unstable energy goes on to affect mostly people in the area leading to the next short arc dealing with reversing the effects.
4) Isshin fights Aizen while Ichigo watches, in this moment Hollow Ichigo tries to take over while Ichigo is emotionally unstable (what with all thats been told to him) and Aizen notices, taunting Isshin about his son's eventually decent into Hollowfication, but Isshin retorting that if his son is anything like him he can handle it. Ichigo through another conflict with his hollow may come to something of a truce or understanding in which Ichigo learns his Ressurection and attacks with Isshin jumping out of the way. Thinking himself right Aizen fights off the Hollowfied Ichigo while managing to taunt Isshin about his confidence in Ichigo failing, but when Isshin says something like, "I wouldn't be too sure about that," as Ichigo then speaks to Aizen about not realising he had lost it. Aizen freaks (or at least appears mildly surprised as he does when something like this happens) and Ichigo using the full force of his hollow/shinigami combined powers defeats Aizen.
5) (Okay this one seems kinda of fandomish to me) Isshin talks to Ichigo and gives him confidence, and with an inner conversation with his hollow and Zangetsu (we haven't seen either of these guys for awhile now have we) Ichigo in a moment of true unity with himself hits Aizen with all he has, and with his reiatsu being twice a captains as well his power counteracts the Hogyoku leaving Aizen vulnerable and BOOM Ichigo wins.
Actually Might Happen - 6)Isshin fights Aizen for 3-4 chapters and wins, while Ichigo is given Gin to fight for something to do but can't beat him and when Isshin pushes Aizen into a corner Gin lives to Aizen's expectations and stabs him in the back and escapes, becoming the sneaky villian in the next story arc.
7)While Ichigo and Isshin attack Aizen, a Garganta opens up in the distance and a partially or fully healed Grimmjow walks through it. Scene goes back to Aizen vs. Kurosaki's fight where Aizen is matching the two when a Gran Rey Cero blasts through their fight missing them and decimating multiple buildings or impacting on the barrier around the town. Ichigo is shocked to see him, Isshin acts goofy complaining that could've hurt someone and Aizen ask's Grimmjow if he thinks he can honestly do anything against him. Grimmjow then says something similiar to what Noitra said about arrancar power doesn't stay the same before going into his Ressurection and going to attack Aizen, but instead of aiming to injure him Grimmjow aims for the Hogyoku and breaks it, the release of energy directed at Grimmjow blasting him away. Now without his regenaration Isshin and Ichigo manage to defeat Aizen. Ichigo then checks on Grimmjow who turns out to be slowly dying from absorbing all of the Hogyoku's energy (a character as significant as Grimmjow needs to have a slow ending) and after a short conversation about how he admits to himself that Ichigo is the stronger he passes away. Thinking the war over Ichigo and Isshin don't notice Gin until he has taken the seemingly useless Hogyoku out of Aizen's body and leaves without a word.
8)Aizen and Isshin have a short conversation about their past history, and before Ichigo can ask his father anything Isshin jumps into battle to fight Aizen. Before Ichigo can join the fray Urahara appears stopping him, announcing that for now he should sit back and wait. Turning around Ichigo sees that Yoruichi and Tessai (tiny chance Ryuuken as well but this I SERIOUSLY doubt) are behind him. Yoruichi makes a teasing comment to how Ichigo has fared and if Ryuuken is there he comments on how poorly the shinigami have performed up to this point, maybe directed at Ichigo. Scene goes back to Aizen vs. Isshin who are seemingly going at it before Isshin releases his shikai (not going into details about it) and begins to slash apart Aizen, but with his regeneration Aizen still holds his ground. (Okay I'm going to actually include Ryuuken now) The quincy the appears behind Aizen and fires a hail of arrows at the villain who dodges only for Isshin to appear above and slash downwards with force. A Gargantu opens and a healed Chad, Renji, Ishida, Rukia and Orihime enter the living world, Ishida shocked to see his father helping out against Aizen while the others run ahead to the fighting. Yoruichi however notices them and like Urahara stops them from entering the fight, but Orihime begs her to allow her to get close, which Yoruichi grudgingly agrees. Isshin and Ryuuken still fighting Aizen Orihime tells Urahara of her plan in which he agrees to it. After several more panels of fighting the father's then disappear using shunpo and the quincy variation revealing Urahara standing before Aizen and activates his bankai. (Seeing as his shikai revolves around the manipulation of blood and he told Renji that his bankai doesn't give people strength makes me believe it might have the ability to weaken an enemy through manipulating the blood in their body or draining it to some effect.) After being hit by the bankai's ability Aizen falls down to the ground where Orihime approaches him, struggling with the thought of what she needs to do. Aizen realising what she is planning tries to screw with her head and make her lose confidence but with all her friends around Orihime gathers the courage to use her abilities to reject the Hogyoku's existence, and as it is now merged with Aizen that means him as well. Then comes several chapters showing the aftermath of the war.
Okay now that looks a lot better, an empty blog can be such a sad sight...