The real question in my mind is can the EU survive this amputation? It's not very functional and appears incapable of reforming itself. It's most serious problems, I think, are lack of unifying political and economic institutions. With nationalist sentiment running high, any chance for reform seems remote. The whole shaky contraption could easily come apart.
I suspect England will wake up with a major hangover, but I guess that it is unlikely to be of much strategic or economic importance in the future.