A few thoughts.
Group identity is historical. What we call the French and the Italians, etc arrived at being such over a course of history. They were previously composed of other identities that over time coalesced into their current one, which to many seems just a given. But it is not.
So, if the Celts and Gauls and all the various Gothic tribes could eventually become The French, it's possible that the various EuroCaucasians might one day become The Whites. Not in the sense of a single state, but in the sense of a single people with national tribes. Many Europeans now think of themselves as Europeans. That was not always the case, of course.
I know of no group identity, no matter how strong, that does not include internal divisions. This is human nature. I do not imagine some kind of otherworldly homogeneity.
Vanguards play a role in identity formation. I certainly don't expect the vast majority of EuroCaucasians to wake up one day and sing Kumbaya. Many --perhaps even most-- are lost and would rather die and have their lineages disappear than commit CrimeThink or relinquish their more particular grievance histories for the sake of racial survival. But if the situation continues to deteriorate and our demographic and civilizational precariousness is absorbed (we are currently no more than 10% of the planet and the number of child-bearing females is even smaller) , a vanguard might have a galvanizing impact.
Identity is also created by opposition. When it becomes clearer that the rest of the species sees us all as White, our differences being trivial to them, that might also create a greater sense of racial identity and solidarity. Being hated is often a spur to group identity formation.
Stranger things have happened.