Saudi Arabia will make a big push to host a major event in 2030, they have already made a bid to host the World Expo 2030. I think they will definitely get one event, either the world cup or the Expo, maybe even both since they are crazy and rich enough to do it. Egypt is too broke to host the World Cup so they will relay on Saudi Arabia to fund the whole bid.
It will be very interesting to see how much both countries will change by 2030, since both are going through challenging times at the moment.