Hard telling. Maybe all the snow will have melted by then.
If the weather co-operates, it could be fantastic. If not, well you know. My guess is winter is starting later then conventional wisdom suggests. Still, when it does come, look out. Going NOBO you'll be out of the big mountains by October and that should help with the risk factor. Better have an extra day of food on hand in case you get stuck.
I did the northern 100 miles starting labor day weekend (not a good idea). Had a brand new 20 degree bag. Which was fine at first, but then I had a 20 degree night and it was a bit marginal. That was just into September at 8,000 feet. How close do you want to cut it and how much do you want to suffer in case it's cut too close?
I'd bring waterproof mitten shells too. Keeping your hands dry is a big help in a storm.
Man, I really want to go back there and try again before I'm too old and lame. Which doesn't give me much time...