Was Urahara's Bankai ever revealed or hinted at? I used to watch and read Bleach before, but I stopped following the series after the defeat of Aizen.

Urahara's Bankai is a mystery to me, and since I'm no longer updated, I don't know if there's more to tell on Urahara's abilities.

Has there been an update on what we know about Urahara since Aizen's defeat?
As of yet, Urahara's Bankai has never been revealed. We know that he is capable of it, but he has never actually used it on-panel.

Back when Ichigo was still working to attain his Bankai (Chapter 132), Yoruichi informed Ichigo that Urahara gained his Bankai using the same training method, and did it in three days.

Later (Chapter 224) Sado comes to him for training. Urahara tells Sado that he needs to train against a Bankai in order to improve. He then assigns Sado to train with Renji, saying that his own Bankai was not suitable for training. This implies that his Bankai is either absurdly lethal, or may not be a combat-focused weapon (like how Unohana's Shikai is a flying ray medevac thing).