Single Pilot
The handling problem under these circumstances probably does warrant some training which, as far as I recall, was never addressed in any sim session.
25 years ago I was a first officer with only about 50 hours on type when the captain keeled over. He was a hefty and opinionated old timer and steadfastly refused to wear his shoulder harness en route.
By great good fortune, the senior FA happened to be standing on the flight deck and was able to pull him back clear of the yoke (she was a well built girl and I often theorised that it was her proximity that caused him to collapse!).
We assumed he had had a heart attack.
With about 30 minutes to run I could see no suitable airport with any appropriate facilities for a diversion so we continued and had the ambulance and crew standing by.
The aircraft was not an especially complex one but I do remember being as busy as a one-armed paper hangar as we descended into a busy terminal area. A bit of practice here might have come in handy as most of my flying previously had been with two and three man crews.
Happily, the heart attack proved to have been relatively minor and he recovered.
My deepest sympathies go out to Mike Warren's family - and also to his captain for whom it must have been a deeply upsetting experience.