What will happen in the Middle East?

We are presently witnessing what the Middle East does when it is overpopulated historically back thousands of years. What has historically happened during overpopulation cycles in the past is whole tribes, religions and nations are completely wiped out to the last man, woman and child (unless women are taken to impregnate to raise more soldiers).

So, it is quite likely that we may see whole tribes killed (we have seen this), nations killed (we haven't seen this yet) (unless we are talking about the completely failed states of Yemen and Libya). We have seen all the men and boys and children and older women killed in a tribe and only the women between the ages of 9 and 40 or 50 kept alive to breed with to create more soldiers in the future.

So, if history is any guide regarding overpopulation this is what we are going to see more of. Will Saudi Arabia and Iran still be there in 10 or 20 years?

It's really hard to say at this point. I think a better way to put this is likely "Everything in the Middle East likely will change in some major ways". We are  presently witnessing the beginning of something as extreme as World War II in the middle east and I don't see it getting any better for a long long time (like 10, 20 or 30 years at this point).