PS is the ultimate stage of Susanoo. We have no evidence whatsoever that PS needs something else besides mastering Susanoo. Saying Madara has not been seen using PS before the Vote fight is pointless, since we did hardly see him fighting before Vote at all.
Sasuke has Susanoo, and has been steadily improving it over the course of the series. So, even though he didn't use it yet, it's very possible he might get PS.
Sasuke has Susanoo, and has been steadily improving it over the course of the series. So, even though he didn't use it yet, it's very possible he might get PS.