Definitely go down, maybe not right after the segment. Why do I think so? Open the weekly chart and realize that for very large growth we need a very large drop.
There will be definitely a drop but after the Segwit it will get back and shoot to the moon. More than 80% is in support of Segwit so I guess the community is behind the decision and it will be successful. Hopefully, it will solve the problems which we are facing right now and that will bring more people into crypto world.