So, with UA, they will sometimes zero out lower fare classes (even when the cabin is empty) and make them available closer to departure --usually around times they predict will be busy like the holidays.

I've seen this happen with OZ sometimes, but it doesn't seem like SQ does this.

Lower fare classes will disappear after all the tickets in that fare class have been purchased... right? Or does SQ do the same thing UA does and release lower fare classes closer to departure?

Anyone have insight on this?