We cannot understand ecclesiology as some kind of empty theoretical construct. We have to consider historical precedent before we launch into crafting a theory. For example, during the Meletian schism in Antioch, there were two competing claimants to the episcopacy who were supported by different churches. Rome and Alexandria preferred Paulinus (who was the bishop selected the Eustathian faction). Bishops in Asia Minor (like St. Basil the Great and St. Gregory the Theologian) supported St. Meletius. Even more confusing perhaps, St. John Chrysostom received ordination to the diaconate and to the priesthood from different sides of the schism, being first ordained by St. Meletius to the diaconate and then being ordained by Evagrius (the successor of Paulinus) to the priesthood. Eventually, Evagrius died, and Flavian (St. Meletius' successor) successfully prevented the Eustathian party from electing another bishop. St. John Chrysostom would go on to use his influence as the bishop of Constantinople to secure imperial support as well as the support of Rome and Alexandria for Flavian (despite the fact that he several years earlier had rejected communion with Flavian in favor of the Eustathian party led by Evagrius).
So now take whatever theory of ecclesiology you have in mind and ask the following questions. Which bishop of Antioch was legitimate? Was one faction completely outside of the church and another in sole possession of the fullness of the church? Supposing that to be the case, what about those who wrongly accepted the faction outside of the church? Did they become schismatics? Must we therefore, for example, suppose that either St. Basil the Great or St. Athanasius was a schismatic? If you have arrived at an ecclesiology where either St. Basil or St. Athanasius was a schismatic, perhaps it is time to take a step back and reconsider your theories.
Analogously now, there are two competing factions in Ukraine. Both sides have canonical arguments for why their faction is legitimate (though in my opinion, the Ecumenical Patriarchate's canonical justifications are quite flimsy). This is by definition a schism. But as with the Meletian schism, the present circumstances are not clear enough to conclude that anybody has found himself firmly outside of the Church. We also can enumerate, if you will, a secondary schism (caused though by the first) that is of a different quality from the first schism, which is that the Russian Orthodox Church is refusing communio in sacris with the Ecumenical Patriarchate and her clergy (I am told this does not extend to laymen under the canonical jurisdiction of the EP, who are permitted to commune at Russian churches).
To me it seems that the only ecclesiological opinion which does not make complete nonsense out of church history is that the mere existence of a schism does not necessarily imply that any faction is completely outside of the Church. The Church must first judge that a faction has departed from her confines by an obstinate refusal to submit to her judgment on how the schism should be resolved, and even then, perhaps it is possible for the church to receive such a faction back by revising her judgment since the cause of schisms are ultimately matters of discipline and not matters of belief.
