Hungary, Poland, The Czech Republic, Slovakia, the Baltic countries will be the last refuge for Christians in Europe as Western Europe collapses, probably within fifty years.
But even if they try to unite, they're going to have a difficult time in decades to come defending themselves against jihad, both from the west (the formerly Christian but now islamic countries such as France, The Netherlands, Italy, and Germany) and from the southeast (Turkey).
Ironically, we may see the Christian nations of Eastern Europe again come under the sphere of the Russians. Only this time, it will be "by request" and by voluntary treaty...