There's clearly some market for this. The food giants haven't yet entered because it's risky, and the supply chains for the ingredients still being developed. As soon as Soylent is successfully shipping safe product, however, the big companies will jump in and crush Soylent Corp with their lower pricing and higher profit margins due to their scale of production.
Every single time Soylent is mentioned the other companies selling the same, or better, gloop are mentioned.
Here's Nutricia (https://www.nutricia.co.uk/fortisip//)
Here's Abbott Nutrition (http://abbottnutrition.com/brands/abbott-brands)
Here's the consumer site for Ensure (http://ensure.com/)
These are, despite what some people say, complete foods that can be used to replace all food you eat.
The idea of drinking Ensure for 90% of my meals scares me for the same reason Soylent does. The unknowns are too much - small startup or major pharmaceutical company alike.
https://en.wikipedia.org/wiki/Plumpy%27nut
I have no idea why this Soylent thing is considered new.
(https://www.wfp.org/nutrition/special-nutritional-products)
They can compete too on "nutrition". Talk about how the big corps cut corners (which they will) and how that reduces the utility of their finely tuned formula.
Doesn't have to make sense, just has to sound plausible.
Ha, good one!