Aizen's definitely not dead. But I do think he may actually be injured... if only slightly. If Yoruichi, Urahara, and Isshin don't start actually injuring Aizen, even a little, soon, then they're never going to hurt him.
I agree that Getsuga Tenshou is probably a family attack thing. One important thing to note is that Getsuga Tenshou is a Shikai ability. And we didn't see Isshin release his Shikai. Also, Isshin's sword looks exactly the same as it did the last time we saw him fight, when we knew that he hadn't released into a different state.
This means that Isshin's Zanpakuto, like Ichigo's, is in a constant Shikai state, which would make sense because Ichigo and Isshin are, as stated before, father and son.