That is indeed the fulcrum on which the prospects for reunification turn. Note that much in the liturgical reform of Vatican II is of no concern to the Orthodox, who in any event will keep their own rite, but the orientaton (or is it occidentation?) of the priest is, unfortunately, a clear sign of disunion.
Seems like a petty disagreement to me, not big enough to separate God’s family for so long. I used to go to liturgy committee meetings when I was a church musician, in high school and college. One reason I never became a full-time professional was that I couldn’t stand bickering over what was going to be done, in what way, and when, when there were much bigger fish to fry— like saving souls.