Battleworld notwithstanding, your correct about his current state of apparent non-existence.
On Battleworld, there are multiple instances of Simon: AoU vs Zombies & Korvac Saga.
Hope post-SW is better for Simon. :\
Yeah, I'm pretty sure that pre-Battleworld, Simon's body was gone, and his powers and psyche were magically and mutantly absorbed by Rogue. So she's now half Rogue and half Simon, back with powers similar to her Ms. Marvel days (though presumably considerably stronger, if she has Simon's power now).