Even if they'd allow a crowdfunding campaign I don't think it will bring even close to enough to keep this game going for even a couple of months.
Apart from that, starting march 2016 they are going to lose about half if not more of their revenue by console players who are definitely not going to jump to the pc version.
I am pretty sure that they've already calculated for that.

Personally, I have already made my peace with the fact that no new content will be released after november and that I'll spend the next maybe 3 or 4 months after finishing up a few goals and calling it.

My personal long term option is simply moving on.
It has been a good 11 and a half years.