It is not uncommon for local jurisdications (Internatiional ventures) to pull concessions and retender them.... in oil and gas and mineral extraction - but this is mostly in cases where the Junior or Company has not followed through on their minimum work committment plans and/or are having trouble raising cash to fund their ventures or are, simply, dragging their feet. The local governments want to see cash and investment being spent in their countries; transfer of knowledge; employment of locals; and proof that the project is net benefitting their Country.
CEE satisfies all of the latter. Egypt (or any country) needs and wants to have foreign investment and if they were to Nationalise CEE then they would scare off all other foreign investment and kill any other JV projects. They don't want to do that with CEE.
Nationalists can scream and yell and try to change it - but if they prevail, the funds dry up. Doesn't appear to me that Egypt is going along this path.
Certainly, new projects will have / may have tougher terms - ones that more greatly benefit Egypt - but they will have to compete for funds against projects elsewhere in the world. Typically, existing contracts are left alone and grandfathered.
I see CEE as being safe and recovering - hence my investment when the share price tanked. I have seen this before where arbitrary taxes are levied; ministries don't talk to each other; etc... and eventually it gets resolved.
CEE should recover to previous highs.