We know the Great War is coming, which means that the White Walkers will need to get past the Wall’s boundaries.
Besides, now that the Night King has a dragon of his own, it’s perfectly possible.
The Night King can assemble as large an army of undead as he wants; it doesn’t matter so long as the gigantic Wall, with its magical fortifications, is still intact.
For the past seven seasons, the growing threat of the White Walkers and their army of wights has felt less pressing than all the civil wars for one big reason: the Wall has remained standing.