Ywhach wins, the end. The way the series was going, that honestly seemed likely.
Or, going the more realistic route:
Before ichigo fights yhwach, we cut back to the seireitei, where zombie izuru is fighting Lille, with the help of the fullbringers, explaining precicely why he is alive (I have no idea what Giriko can do, but considering he can kill people by looking at them, reviving izuru doesnt seem a stretch). Lille eventually defeats Izuru and xcution, then see's aizen and shoots at him. needless to say, that was the last thing he did, and aizen is now out of the chair.
Gerard never goes into his super mega ultra form, and was defeated by toshiro's mature bankai's power nullification thing.
Ichigo uses hollowfication, goes bankai, loses, etc. same as manga.
Ywhach explains his motives to ichigo after curbstomping him and draining his powers, and doesnt do another auswhalen, because that would be dumb, then leaves his minions to finish the gotei 13. Uryuu curbstomps haschwald by explaining the proper use of the Antithesis, and reversing the situation "Had his sword broken and his powers drained" between Ichigo and haschwald, repairing ichigo's bankai, restoring his powers, healing him and defeating haschwald in a way that is only slightly bullshit.
Ywhach goes to seireitei, and finds aizen. they fight for a bit, ywhach has the upper hand, but only slightly. Aizen makes note that he had wanted to kill ywhach, due to him being the soul kings something, and explains what the hell that was all about for no apparent reason, and how it relates to his plan. eventually, ichigo turns up, backed by his friends who actually do things, they all fight ywhach, and win. hooray, everyone lives.
Except Yamamoto, Unohana, Rose, Kensei, The Sternritters and Nemu. ans sort of Sajin
Cut to the future in a bonus chapter. everything is happy, Renji, rukia, shuhei, izuru, isane and iba are now captains, hanataro, ikaku and akon are VC's, Aizen is the soul king, no pointless ywhach returning, and ichigo is married to whoever you didn't ship. The end. nobody cares.