If it goes 80% that honestly would be optimal otherwise it goes into major uncertainty of what could happen over the course of the next two months.
80% pushes us to adoption of 100% by November 1st and the block size pushes to 2MB instead of 1MB effectively doubling the amount of transactions it can take per block. It would be a positive thing for bitcoin but only a very temp fix to fees and transaction times something else would still need to be done.