Honestly, if we were unaware of the ending weeks before the final chapter, I really doubt the majority would be okay with a open ending.
Most people spent too much time, I spent too much time, getting threats, repeated arguments, and debates, for an open ending. I talking shipping wise. It would just be like Final Fantasy and VK, the shipping wars will never end. Shipping wise, I rather a conclusion, even if I end up in the losing side because what I hate most is not knowing in a open end. I might believe NS is canon, but opposing shippers will believe their ship is canon. And I can't argue against that because NS isn't canon (if open end). Plot wise, As long as everything is answered, I'm okay. But I don't think I'll have the motivation to continue shipping NS because I spent five years wanting NS to see them together. Open end to me is just like not being canon, because I have to live through FF and art, fanon in general. The only perk would be SS and NH not being canon, but I still feel that I wasted my time getting attached for so long.
I already been through ships being canon/ non canon. NS was the first ship I really put so much time and dedication towards, and by them not being canon, it taught me not to put so much effort into parings in shounen in general, because it can become toxic, and I won't lose sleep over mediocre shounen were the author could give a crap about romantic development.