Azazyel
If Gensokyo fall if you go deep lore it also mean humanity Sacred Gears will collapse in a sense after all Biblical God is death and Gensokyo is a support realm for the supernatural that include those outside(aka God System) the only sacred Gears that I see won’t collapse is those on devils or soul Longinus like the dragons emperors, Lyakus and Sephiroth Graal… even the True Longinus will collapse as it don’t held any soul at all to support it.