Theoretically, you have the strategic option in Egypt of trying to undermine the ability of the regime to govern by attacking the security forces, the army and the police, government buildings and public infrastructure.
You can destroy any confidence the population may have in Sisi, and possibly even the confidence of investors, by turning Egypt into what is referred to as a “failed state”.
This is not a terribly complicated undertaking. Security forces must operate in a very formulaic manner; they are predictable and adhere to easily identifiable patterns.
If you have the weaponry, you can create scenarios that will enable you to inflict maximum casualties if you anticipate their predictable responses.
You can blow up power stations, target oil facilities and pipelines, police stations, etc, etc.
The government will respond with increased repressive measures against the general public, more violence, and more atrocities.
It is conceivable that foreign companies will withdraw from Egypt due to security concerns. If it becomes too dangerous to move goods through Egypt, companies may opt to suspend using the country as a logistics hub, and possibly shift elsewhere, if there is a viable option.
This process would likely go on for at least a decade, probably longer. There would be tens of thousands killed, and millions displaced.
Egypt would emerge at the end of the carnage with a profoundly degraded military capability, like Iraq, possibly patrolled by UN or NATO “peacekeepers”, a completely devastated economy, and very few prospects for independence.
You are not Somalia. The international system cannot ignore or leave you. You are too big, you have oil, you have the Suez, and you are on the border of Israel.
Your civil war will not end with the establishment of an Islamic state that fills the Western powers with fear and awe. It will end in a negotiated settlement and the installation of a puppet regime which will gratefully submit to any and every demand of international lenders and businessmen. That is the real world.
The difference between that outcome and the present situation is only that there will be more devastation and less hope for the future. But, yes, you have that option.