Things like Soylent are already here. It's not vaporware. Yes it's not perfect or ideal but it's an answer to really inefficient food production whose water and nutrient needs aren't sustainable for a growing population.
But, is it? The ingredients include oats, grapeseed oil, soy derivates, and whey. I'm sincerely having trouble seeing how this represents more efficient food production.
In fact, it would seem to be less efficient from that perspective: it still requires the resources for crops/farming, derives isolates from foods that are otherwise more whole (what happens to the rest?), then adds a degree of processing that requires still more resources.
Isn't it more efficient to just eat whole foods rather than extracts from various foods that, by definition, require energy/processing to obtain and must leave some waste in the process?
Maybe it's more convenient from the consumer's perspective, but I don't see how it solves the production problems you suggest.
I'm not telling you to not eat Soylent or that it won't potentially be great for the human race. But again, we don't know.
Edit: fixed wording Edit: What if they get something wrong like including trans fats? I know this a "playing to fear" argument, but there is a long history of industrial foods being not healthy. It just takes a new generation of suckers to come of age.
Sure, said peasants probably had vitamin A deficiency—but they managed to live long, mostly-healthy lives despite that. Which is my point: we don't need to get "food" perfect in order to ensure that 10x as many people as today can live "long, mostly-healthy lives." It's not unethical to feed starving people food that's missing some micronutrient we aren't yet aware of, because they'll still be better off than if they were starving. The human body is hardy.