#1 It eliminates the Israeli myth that the Palestinians want their state to encompass the river to the sea. #2 There is a possibility that there will be a majority of UN Nations that accept the declaration. #3 Israel's pariah status becomes larger if it imposes sanctions and illegally annexes more Palestinian territory. #4 If Israel refuses the declaration and annexes more occupied territory, it is left with only two options: Eliminate all non-Jews from the river to the sea (by force, expulsions, exterminations etc), or accept one binational state from the river to the sea with all inhabitants entitled to equal rights for all regardless of national/religious orientation.
NATO backs Turkey's fight against ISIS (Reuters)
from the article: Palestinians under world pressure not to declare state unilaterally