Saw 6 is needed to finish the story, with how things ended in 5. It's clearly two separate trilogies, whether you guys like them or not. But please, NO Saw 7. End it on a high note with a happy ending for once, please. I want to see Jill chain Hoffman to the bathroom.
Part 5 is definitely the middle part of a trilogy and follows similar story structures from many others. If you think about it, part 5 ended a LOT like Empire Strikes Back--a smart-assed, rebellious hero was defeated, the villain won, new revelations of backstory were made, and virtually no hope for salvation was in immediate sight, but...as Yoda said, "there is another", a female we all might have overlooked--Jill.