I hope there is still a place for him in the Sens org, even if it's something as simple as part-time adviser.
A huge element of fighting major illnesses, even if they're terminal, is your attitude towards it, and having something to work towards. I hope Bryan keeps busy if that's what helps him through all of this.
As for his replacement, I know a few of my Usher buddies are saying it'll be Shero, but that's still speculation on their part, regardless of how much closer to the team they are than I am at the moment. That's just their hunch.