Collapse due to what, Even if Egypt bombed the dam. I doubt the Sanctions would be hard enough to lead to state collapse. Even if it did it wouldn't happen in days and would stop the moment Sisi is dethrone.
What I am saying, is given the evidence I have provided, Egypt would lose the war. And the dam is a very sensitive issue among Egypts generals. Should the very unlikely event occur it be a success, El sisi might be remembered as a great statesmen, or a butcher (giving i already gave you evidence of the mass flooding, which could prompt un intervention.) However, its unlikely they even get passed Sudan, and with the warming of ethiopian eritrean relations, Eritrea will likely not allow free passage.
You would get at worse a series of coups. What ideology are these generals promoting to get support for a civil war.
No. There does not need to be ideologies. Look at Somalia, besides al shabab, its competing warlords, look at Libya, besides daesh and al qeada, its also apolitical warlords.
They would still have to deal with hostile factions in the Sinai and an open Gaza border on the Egyptian side.