Survival was a thing on the server some time ago, you'd have to go thousands of blocks out just to set up a home and most ores are taken and it's very hard to find any, and be reminded this was back when there were 400 max players. It's fairly difficult to make a survival server with the amount of people cube has on it and I just don't see it as something that could easily work, people could troll you for fun and ruin your progress. I personally would like to keep survival to single player or smaller servers. Also, flying would give ranks a huge advantage in gameplay, which isn't following the EULA guidelines, as they wouldn't need to build up to get out of ravines and from my experience, giving /fly to players while they're in survival allows them to have no fall damage so that's another huge advantage. Overall I don't think this would end well.