Well, it seems that . . .
For those who subscribe to a multicultural/internationalist/politically correct ideology - No.
For those who are more traditional/nationalistic - Yes.
From my own perspective, I would argue that there have been many threats to Europe's existence over the past two centuries and that the current mass immigration crisis is merely the latest noticeable symptom of a rather tragic and horrendously protracted ailment.
I would add that when it comes to matters of its existence, Europe has become its own worst enemy.
A toxic blend of wars, guilt, self-loathing, sub-replacement fertility, secularism, debt, horrendous economic policies, hedonism, and subverise/suicidal ideologies such as political correctness have damaged Europe far more than this current mass migration has. One could claim that the migration crisis could not have even developed were it not for the combination of some or all of the problems mentioned above.
The only thing the migrant crisis threatens to do at this point is to turn Europe's gradual and drawn-out decline into a quick and sudden one.