Egypt has nothing to gain by breaking the Peace Treaty with Israel. It would only invite Israeli intervention, Lebanon style, on its territory which would force Egypt to go to war with Israel. A war that it would lose and could lead to the reoccupation of the Sinai but only after large casualties on both sides. Furthermore, a state-of-war with Israel, live or not, could only undermine the other aspects of the popular uprising there. That is to say, how can work be done to improve the economic prospects of Egyptians or improve the civil rights situation there under a state of war? The opposite would occur.
Islamic State militants blow up ancient Arch of Triumph in Palmyra (Reuters)
from the article: Jordan's Abdullah: Egypt could break its peace treaty with Israel