Who was the villain before Aizen…?
No one.
uhh. byakuya and soul society for executing rukia.
but it turns out Aizen killed all the court judges and shit and fakes his death perfectly etc.
With how powerful Aizen seems, he should stay the main villain. Ichigo will probably get something to combat him. I mean he did send ulquiorra and yami to gather info on him. There is something he will probably get later to combat Aizen.
I'd rather him write ichigo with some perfect ability to beat Aizen's, than to have a bigger badder dude controlling Aizen. I mean it still doesn't change the fact that Aizen can't be beat.
And if someone more powerful can beat Aizen, and Ichigo can beat him. by the transitive property, Ichigo could beat Aizen anyways. So there is no need for a middle man.
There is honestly no believable way for Ichigo to end Aizen at the current arc.
Bleach isn't ending this arc. I mean half the characters are just about dead and the top 4 espada haven't even gotten serious. Only 2 have released. Not to mention all the shit with other characters that needs to be tied up,
People saying it is ending here are just dudes who are bitching about the fighting.