Imo i think The philo mats MB prices might go back up as ppl find seal grinding / fating boring and useless now.
So assuming the philo mats are now out of the main tome grind route/ dungeons an instances.
Their quantities on the MB might lower thus becoming a more rare thing.
Even if there are going to be new myth materials, those old philo might be of some use to someone. So don't count em out yet lol