They don't have the military means to do so. They would be slaughtered in the field.
Instead we'll see a serious uptick in terrorism and rockets from the north and south. Their intent is to bleed Israel until such time as they can obtain nukes.
Its not the 70s anymore. Egypt alone has a very effective and well trained modern military. As recent as 2009 we gave them some $2 billion in military aide. Not to mention training with them for the past 30 years.