I wasn't even thinking of the future fantasyland! So...
...don't forget the invisible elves who will supply the burgeoning milennial resurrected population with pollution-free plastic for beach balls and shoes (which of course will no longer be made of leather from slaughtered animals)...
...and the millions of hand-powered bellows-driven blacksmith shops, also presumably run by those same invisible elves, who will supply the nails, horseshoes, farm implements, etc. for those 20 billion persons...
...and the enormous textile industries that somehow manage to produce ethnically-accurate clothing in vibrant colors, of course all of which are pollution-free...once again run by those invisible elves, as the JWs & resurrected ones will be too busy constructing 5000 square foot homes and carrying baskets of fruit around all day...
...and of course don't forget the geological changes to come! All 20 billion people will have either mountainside or beachfront property upon which to build their 5000+ square foot homes...which, by the way, are cleaned by invisible elves...