In "Ocean's Thirteen", Reuben is muscled out of a casino/hotel deal by Willy Bank, the film's antagonist. Unlike when he was screwed over by Benedict in Eleven, Reuben is completely destroyed by this double-cross, thinking that Bank was an Old Friend who adhered to the Vegas code of honour like he does. He only ends up signing the papers after being implicitly threatened with death. This betrayal leaves Reuben financially ruined, the stress of which causes him to have a heart attack. It's heartbreaking to see such a vibrant, clever man brought so low, and his disgrace ends up being the catalyst for the heist.
After this occurs, all the members of the Eleven drop what they're doing immediately and congregate around his bedside. They all try their best to help him get better, but they're all clearly saddened by the circumstances.
In a more understated way, it's also quite sad to see Reuben sacrifice his personal style (with smaller glasses and suits in more muted colours) in an attempt to adapt to the world of Bank and a more modernized Las Vegas. This makes it all the more heartwarming when he returns to the style near the end of the movie.
It is revealed in Ocean's Eight that Danny apparently died sometime before his sister was released from prison. The sadness of this is undercut somewhat, however, since Debbie has her doubts.
Whether he's actually dead or not, it's shown Tess did not reserve an adjacent crypt.
