I think its far away enough, But if Shenzhen wants to build 600+ or even 500+ in this area, it might be hard. Every single position will have have to be exact, or else crashing into buildings or airplane hitting part of the building and while lands breaks up and destroys the airport. There are probably 2 best way of solving Qianhai's problem, one is to build huge amount of 300-499m skyscrapers, but with different design, no boxes. Or they can build another commercial airport (probably not).