The Absolute Primacy of Christ is the name of the thesis that God willed the Incarnation as His greatest work from all eternity, for its own sake. Bl. Duns Scotus was its great advocate, and Danny Garland has outlined his thought in a post on Irish-Catholic and Dangerous.
Finally, Mark Shea and several commenters at Catholic and Enjoying It! have taken up the discussion; in particular, Scott P. Reichert suggests:
this division is at the basis of many of the differences in Eastern and Western theology--and I'm speaking here of differences that were evident before the Schism.
So while I'm not altogether sure the counterfactual question, "What would have happened?" is well-posed to begin with, the larger question of why what did happen happened is by no means a trivial or dusty point of scholastic method.