It's possible PLA Navy and marine will retake those bases if it comes into shooting war like Paracels. Therefore those reef building by whichever nation will come in handy for the military victor because it lays already the foundation for future occupation. I foresee a large PLA base like US base Diego Garcia near the Indian continent, a super base.
I do hope Vietnam or Philippine start it first (I know it's bad, but I think it will happen), and China will claim it during "counter attack" as "self defense". Would be interesting the whole place turn into super base for China military as staging post.