[Spoilers] Theories on upcomming events in the manga - what happens next/what do you think will happen

Title says it all really, what we know/ think will happen, what characters will appear and where will they go

Ive started my third read through of this series and ive been wracking my brain over two things in particular:

Who the behelit is destined for that guts carries and Will Theresa from the beginning hold her promise and come to kill guts one day?

My bets on the behelit falling into a dying party member causing all hell to befit Guts again.

Also was Skull Knight a product of the armor do you guys think? Or did he gain his seemingly agless body some other way.