Pirates 1 villain: Barbossa (killed)
Pirates 2 villain: Davy Jones
Pirates 3 villains: Davy Jones/Beckett (killed)
Pirates 4 villain: Blackbeard (probably killed by Barbossa)
So...Pirates 5 villain: Jolly Roger???
I'd say that would be a perfect villain for the next movie, I mean he wants revenge on Jack. It sounds good to me.