How many others?
I’d say that the EU’s purpose of consolidating the Teutonic bloc has been met. That is what must be reversed.
I do believe that the precedent of Britain leaving would influence others to do so. I don’t believe Europe will be a cohesive entity over the long haul.
Do I think there are others that would drop out this week, or within a month? No. I do believe others will leave and I think Britain will have paved the way for that, if it leaves.