This death was very sudden as well as sad. However, I noticed Drake looking frail and skinny since his return to Salem through Chad's Abigail arc. The signs were there, people noticed. But a press release said all was well and fears were alleviated. (Pancreatic) Cancer can be unpredictable. Hopefully, we know more soon about his battle for it was clear he wanted to continue working.
That being said, film production is 6-7 months ahead of the airdates. There's still more John Black to come. How the show will handle the exit depends on the angle. We've had notable DOOL veterans pass on in a span of two years, notably John Aniston and Bill Hayes, and the writers find ways to write them off with dignity while also holding true to their character. Victor dies in a sabotaged plane offscreen while Doug will (very) soon be revealed to have probably died in his sleep in the Horton House like Tom Horton in 1994. I'd say John's exit will involve either a Black Patch case that ends in his death or maybe life will imitate art and John will have cancer and pass offscreen with Marlena at his side. Although, I can't see Drake letting John succumb to the disease onscreen, the possibility is there. Regardless, another great character and a great actor have left this world.
My first experience with John came through the Salem Stalker arc. Initially I was team Marlena/Roman but when the Island arc came on, seeing Drake becoming a total bad--s, I was team John/Marlena for life even with his rug addiction arc. Watching his past work before then also showed how well his character was handled in certain arcs, complex as they may have been. The last four years since returning to the show were good and John's wit and action star motif still gave me reasons to come back.
DOOL will truly not be the same without Drake. He will be missed and my heart, from one actor to another, goes out to his colleagues and family.