The Western part of the Roman Empire was actually less urbanized than the eastern part, so the government in the West seems to have had cash flow problems before thay banned the monastaries and confiscated their assets. Its true that had more agricultural land than the East (in an era when agriculture equalled wealth) and a much better army, plus though its hard to believe the East at the beginning of the fifth century was more ridden by religious conflict. But get enough weak emperors and you get a cash starved government that the Church, the wealthy landowners, and even the Germanic tribes that they incorproated into their army can push around.
My guess is what happens is that the Germanic tribal leaders just stop paying attention to Milan and eventually set up their own kingdoms, similar to what happened in northern China in the fourth century AD. You probably won't see so many reconstructions of the empire that have been a feature of European history. A potential wildcard would be the Arabs succeeding in adding a few provinces of the Western empire to the Caliphate.