[tvmalsv]

It's also worth noting that, in a sense, the shell is actually shrinking. Every moment, more of our observable universe disappears "beyond the veil", so-to-speak, as the universe on our side of the edge transitions from near-light-speed to beyond light-speed outside the shell. (I know that's a sloppy way to use the speed of light, but it works for me.)

[xelxebar]

Small nitpick, that shell---the Hubble sphere---is shrinking due the accelerating expansion of space. Constant expansion cooresponds to a constant Hubble radius, and decelerating expansion with an expanding radius.

[tvmalsv]

Good point, thank you.