I'm afraid I'm leaning toward "temporary." At best. I certainly doubt Mark of Ephesus was the lone wolf holdout the record appears to make him; no doubt he was a point man and possible goat should the resistance in the East fall through with the Emperor taking stern measures to make it so. The point being, the measures involved would be sterner than bringing one lone Patriarch to heel, thus costlier.
Meanwhile the leaders of the factions comprising the Western rite bloc at negotiations have their own divergent interests. In addition to schism in the East we might have schism in the West as well.
If somehow, on a high level in Rome and Constantinople, a shared understanding of common interests prevails for many generations, still the various centrifugal forces involved will tend to render the reunion a dead letter, on paper only. And if so, sooner or later people on both sides will be denouncing others as schismatics anew.
Consider how the First Crusade worked out, despite the Popes calling it and presiding over it having a strong common interest with the Eastern Emperor. The high clergy might have seen a common cause, but the western Crusaders who showed up in Eastern Imperial territory were constantly in conflict with the Emperor. Their ambition was to seize new lands to rule themselves; they had little will to submit to the authority of Constantinople. This rambunctious autonomy of the fighting Crusaders was reflected in the crass interests of their clergy as well; if doctrine demanded they recognize the Eastern Rite congregations and hierarchy as equivalent to Roman, then there would be only humble places for the Frankish clerics. As things were OTL, whether they were in alliance with the eastern Emperor or not, they disregarded the Orthodox churchmen on the ground in their Levantine conquest zones, and set themselves up as the new Bishops and hierarchy in general. The Roman Rite invaders were much more ready to negotiate with local rites that on paper were far more heretical than the Orthodox. But the huge doctrinal differences were papered over with agreements to Unitary rites leaving the non-Orthodox congregations largely untouched, except for some formulas bowing to Papal supremacy, and then these Christian populations were included as part of the ruling order of Outremar--much more readily than the much closer doctrinally bodies which happened to submit to Imperial authority in Constantinople, and therefore stood in the way of Latin ambitions.
I haven't even alluded to the Fourth Crusade yet...

Consider it alluded to now.
Aside from conflicts of interest with ambitious and ruthless "Franks," the Orthodox system suffered from other centrifugal forces. Having established back in the days of Constantine that the supreme Roman Emperor would have the final say in matters of orthodoxy and doctrine, it followed that whenever the political authority of Constantinople broke down, the local churches would be adrift, and if they were in regions taken over by invaders who might be barbaric but did profess more or less Orthodox Christianity, the outcome would often be the local kings, whenever they plausibly wielded enough power to look like regional great powers, setting up a new Patriarchate in their own capitals, under the thumb of an upstart king who likely as not called himself a "Tsar." This was probably a very good thing for the survival of the Orthodox rite as such, since it seems nigh inevitable to me that someday Constantinople would fall to a Muslim conqueror sooner or later, and had the "real" emperors been able to make Orthodoxy contingent on their holding power, I guess the churches would have been in big trouble once that power was finally extinguished. But realistically that was not going to happen--the very same Caesaro-papism that made the Eastern Emperors supreme in the church wherever they did hold power also guaranteed that local kings would put themselves at the head of the regions they controlled.
So, the ability of the eastern churches to be herded into a doctrinal agreement (if only one as thin as the contracts forming "Unitate" rites in the Crusader kingdoms) was entirely a matter of the Eastern Emperor holding power; it would be null and void outside Imperial sway, unless a shift in policy made it prudent for a regional "Tsar" of Bulgars or Serbians or Russians to trim his doctrinal sails along with Constantinople's.
If we imagine it happening then, the likeliest thing is that it falls apart in a lot less than a century anyway, as each side outrages the other. (Probably it would be the rambunctious Latins who would offend more than be offended).
If this does not happen, we have to imagine a snowballing ATL where more and more things counterfactual to OTL accumulate. Basically the Roman side of the union has to discipline its followers, and any forces sent from Western Europe eastward have to actually aid the Empire, accepting lesser rewards and status than greedy barons could hope to seize for themselves. It is pretty hard to imagine what succession of revolutionary events in the West could impose that kind of discipline; it is probably necessary to imagine that far less volunteers up stakes and go east in the first place. And yet that the chosen few who do aid the Emperors in the East make a strategic difference, enabling the Eastern Empire to stand stronger and for longer---conceivably, if we can get this rather improbable ball rolling at all, to this very day. And somehow either the two regions evolve separately without jealousy or ambition leading to one side designing to forcibly conquer the other (quite a trick considering the chaos of dozens of major sovereign powers in play in Western Europe! And a presumably unitary Eastern Empire contemplating this fratricidal spectacle without reflecting on the Emperor's Christian duty to bring peace and order to his co-religionists.

) or there is some kind of political fusion, with the imperial claims of both east and west again asserting themselves in a vast pan-European empire.
I fear it is very much cart before the horse to attribute the divisions between eastern and western Europe to the doctrinal split between eastern and western Catholic rites. The latter are a reflection of the former, and ecumenicism is either a reflection of a new unity of political power imposing a new unified doctrine to suit itself, or of an era where religious rite is decoupled from political power pretty completely, and so religious people can contemplate the logic of their position without reference to overriding reasons of state.