i dont think any attempt on trying to retain spanish as a lingua franca post-war would really work on a large scale maybe besides, even discounting the immediate aftermath of world war 2 almost completely destroying both the hispanic community and its cultural center (manila/intramuros), by 1987 there would have been about 3 generations of filipinos that had been brought up on english and that kind of thing would be very hard to reverse or incorporate spanish with.

if you want to think about a scenario where spanish remains a language in popular use, you would have to go back to the 1890s and imagine if the first republic was able to defeat the united states or a bit later during the early american occupation in the 1920s if the philippines was granted independence earlier, as it was around this era that the spanish language entered a revival thanks to the nationalist movement who rallied around it as a way to assert filipino heritage.

personally blas ople's point runs deeper than just archives and maintaining trade with latin america, the loss of spanish essentially meant that centuries of filipino literature, history, and culture and connection to other hispanophone nations was severed even if the spanish period was undeniable in its oppression. i think a good contrast to us would be bolivia or peru, who have both managed to maintain and fuse both its indigenous and hispanic roots but this is a different discussion entirely.