What exactly happens to those who don't last? Are they really completely gone, or is there a chance they're alright?

[Maybe they weren't "really" twins. Maybe he's definitely Jun, and the other was definitely Okuyasu. But reality is rooted in memory, isn't it? So aren't Lonán's memories just as real as Jun's? And those memories are as precious as Jun's memories of summer afternoons at the Alaya Shrine are.]