some Bleach questions?

FGT is the final form of Ichigo so let's not talk about shall we. Bankai is indeed the most powerful release of any shinigami but its not the end of evolution as there is still many forms in Bankai, for example we have seen the three different form of Byakuya during his fight with Ichigo, Hitsugaya also had Four different forms and he is still not at his limit so this tells you that a bland Bankai of Ichigo does had lot of potential and I think its not even close to 25% of its full potential at this moment. Something tells me that if Ichigo learns about his origin (which he is right now) than he is going to learn a more powerful technique than FGT, moreover without losing anything.

FGT is just too overpowered so, leave that aside. If Ichigo were as strong as FGT, he would probably be the Soul King (nah that's exaggerated). FGT is not HIS potential, it was basically Tensa Zangetsu's. Ichigo still has a lot of room for evolving, I mean, he only know bankai for how much? 3 years? He can still improve it and learn of it.

Assuming Ichigo will defeat Juha (who defeated tha old bad-*** Yamamoto), Ichigo must, and will get very powerful so he can defeat him.

Aizen is mysterious also. Hmm, I wonder (Aizen is my favorite character, along with Koyraku and Ulqui)

Evolving isn't always getting stronger. Ichigo is still young and he will get stronger and likely change fighting styles several times before he dies. Even after he dies unless he does something that gets him sent to Hell he will still be learning more fighting techniques as an official Shinigami of the Soul Society. There is also the fact he only recently started to tap into his heritage and that will add now skills to his fighting style and change his bankai even more.