What will happen is that the EU will end up being split between north and south. In fact, we could end up with three "unions" in Europe: one with the Scandinavian countries (Denmark, Finland, Norway, Sweden and possibly the Baltic states), one with the northern park of Europe (Germany, Belgium, France, the Netherlands, Poland, Austria, Czech Republic and Slovakia) and one with the southern park of Europe (Portugal, Spain, Italy, Greece and other remaining EU countries).
The three unions split along historical ‘ethnic’ boundaries of Scandinavian, Germanic, and Mediterranean is very interesting.
I don't think Norway is actually part of the EU.