Well mate, on a big airline with 320 passengers, the pilot and 1 co pilot can also die - yet these 2 people are relied upon for the 320 passengers being alive
so someone onboard with their Commodore 64 flight simulator experience will take over.
Same for the other scenarios companies worth millions must have some contingency plans........ If a volcano erupted in Dundee, would it kill ALL members of YYG ? that's one big bloody volcano there
As to ENIGMA, I don't think "millions" of people rely on ENIGMA nor the website, if that were the case, then whoever owns this would be an idiot not to monetize the traffic
Also their hosting bill would be far higher lol!
ENIGMA is open source, anybody across the world could take over....
As to GameJolt, well again it's the internet, so unless there is a big cataclysm to destroy the entire infrastructure, other people will take over.
So you will be developing games for a long time not to worry !