Funny, Casey didn't do anything but sing on that. I doubt they do anything real without Casey at this point. It was such a healing moment for everyone that I think they'll wait until everyone can be involved in a meaningful way.
I'm fine with Casey just singing. I enjoy Mi Fa Mi more than BTHATS anyway. Weightless Underwater is great and shows how Casey can add color without being one of the main writers.
I thought Weightless was just a B-side from the BTHAS sessions? It's weird that it was teased as being a fresh release for the reunion this year... I've had it since sometime around 2009 when the band did a digital release at least.
This post says it was recorded for the deluxe BTHATS vinyl, and has "everyone actively in the band on the song" So I think this was post Mi Fa Mi.