One of the highest-ranking Chinese officials to visit the Philippines said his country was ready to help President Duterte realize his dream of building a railway to connect key Mindanao areas with one another.
http://newsinfo.inquirer.net/881920/...ndanao-railway

Just my thinking but I'd see this as a very challenging project from an engineering aspect alone.

The next major issue would likely be acquisition of land and location of stations.

At the end of the day there would need to be some huge changes to the issues relating to armed groups.
These groups target electricty grid structures at the moment but a kind of National Railway sytem (even under construction) would become the prime target.

My dream would be 'local' airports with easy access to Davao International.