And Kubo said Bleach revolves around Ichigo.
Scenario A:
He'll probably be nuking Hollows with a snap of his fingers in 2 weeks time.
Isshin got his powers back, he even told Ichigo about Final Getsuga, so he probably used it prior to the series.
Scenario B:
This takes place a few years after 423.
Since we know there is 2 more arcs Kubo confirmed this in a interview around January 10. And further rumors, above show the length of those arcs.
Arc 4/5 (Arrancar to now being 1 or 2 arcs...?): Ichigo trains to regain his powers with the help of Isshin, Urahara, Tessai, Yoruichi and maybe the Vizards.
Orihime have learned Kido.
Chad have more control of his powers.
Ishida received an upgrade to his powers.
Ichigo gets new Zanpakuto, Mugetsu.
We're introduced to Ichigo's fully mastered BanKai, allowing him to mimic the Mugetsu used against Aizen with less power.
Eg. The Zanpakuto merging with him and he'll be fighting hand to hand combat instead. He is trained in Karate so there shouldn't be that much of a problem
Small leftover Arrancar attacks and Ichigo's newfound powers are put to a test.
Orihime lose her hairpins.
Final Arc: New bad guy shows up.
Now since this is said to be finished in 2-3 years I'm thinking something like this:
Year 1 - 1½: Ryouka Team charge into SS to find out what's happening, say Shinigami's stationed in World of the Living doesn't do anything about the Hollows, Ichigo and co. try to contact SS and gets told something like the Shinigami doesn't care for them anymore or something else is happening that makes World of the Living second in line.
Ryouka Team charge SS, again, to get answers and run into the new badguy.
Ichigo battles one of the stronger henchmen and gets another "Rival" enemy in the types of Grimmjaw (What ever happened to him and Nel :eyebrow:
Year 1½ - 2½: They find out Bad Guy actually is Royal Guard, and that Spirit King had planned to wipe out all Shinigami once every XXXX year, and that it's time for wiping them again. This makes Aizen less of a bad guy who, Between Turn Back the Pendulum and Chapter 1 declined promotion, and Isshin also left Royal Guard doing that time. This will also tie in Isshins story which Kubo want to tell, also mentioned in the interview
They launch an attack on King's Realm, stopping the Spirit King from executing the Shinigami.
Year 2½ - 3
Ichigo's hollow having been hiding deep within Ichigo's mind, springs forward to take over Ichigo's body once and for all. Foreshadowed doing both arcs with his hollow powers appearing a bit like they did during the SS Invasion Arc.
At the end Ichigo finally defeats his other half and gains the complete powers, and.... Something.
---
All of this; Completely odd theory from my side.