I recently reviewed a presentation of the Joint Foreign Chambers of Commerce to the new administration in the Philippines.
The recommendation is to turn Clark into the primary international airport for Manila and use the existing NAIA for domestic. Proposal depends on a high-speed rail link from Clark to Manila light rail system. Similar scenario to Narita and Heneda.
There is some logic to this as runways can be added to Clark - it would be impossible to do this at NAIA.
Snowball's chance in my lifetime....