That post is pure hysteria. First no one knows when Gabe is going to die, and even if he live very long he may step down due to old age still.

• also worrying so much about something that may happen 14 years later according to op is unnecessary and distorted thinking.
• why assume there is going to be a power vacuum? can't he and his leadership make pans of succession?
• then believing a whole made-up story going down the rabbit hole of the worst case scenario is again unnecessary and distorted thinking. Is okay to think of worst case scenarios but to take them as if they were real is gifting ourselves anxiety for free.
• in any case, the mental exercise of thinking of some undesirable possibilities allow us to take precautions and prepare to the extend that is appropriate and reachable. Which would be the most efficient behavior that thwarts "actual fear" as OP writes it.