I thought there was such a wonderful symmetry in Miss Rosa taking Vee "out" in the end. Vee came in and disrupted Miss Rosa's life. Much the way Cancer came in and disrupted her life. Miss Rosa had very little left to her except her dignity and Vee showed her callous disregard for that when she twisted her hand puppet (SUZANNE) to spoil her crappy meal and kick her away from the table. Notice when Suzanne did that, Rosa didn't take it out on Suzanne, she turned to Vee and vented.
Think about it, Miss Rosa has been in prison longer than anyone except the "real" golden girls, she must remember this chick from the first time Vee and Red tusseled, and sees the drug dealing/ race baiting the Vee has instituted since she arrived. Taking out a piece of trash like Vee before she herself dies was kismet. Even if TPTB catch her and put 2 & 2 together, the Cancer will claim her before they can punish her further.
Was it as scary or as awe inspiring as last season? Nope, you are right about that. But that level of shock is hard to meet much less exceed, so perhaps it was best they didn't even try.
As for Piper & Alex, I agree with your comment re: symmetry between Alex assuring that Piper would go to prison in ep #1 and Piper assuring that Alex would come back to prison in the finale... but I think both were done "for love". Alex was convinced, against her better judgment, that Kubra would be put away with her testimony and she/Piper would ultimately be safe. Piper was convinced that Alex running free away from Kubra's men would never be safe, and putting her in jail where the "guards" can protect her was the better option.
I think we can guess without Vee, what theme will underscore season 3.
Kubra's revenge.