I am not so sure "a farm-free future with food primarily manufactured via precision fermentation and other scientific processes" is going to feed the hungry masses.
(Of course, for something this important it makes a lot of sense to be slow to change so you can spot any mistakes before they’re important; doing it fast and only then finding out you made a huge mistake will make all the pandemic deaths seem like “the good old days” in comparison).
So you and I agree in that it'd be too expensive to bother – namely that you'd be attempting to erase some of the most important cultural traditions 'for the greater good'.
McDonalds exists and is popular, so traditions are not why I think it might be expensive.
Also traditional food is mostly much younger than it seems. Old World dishes involving tomatoes or potatoes or maize or chillies or chocolate, not possible before trade with the Americas.
We're barely capable of doing it with the current rapacious mega-conglomerate chemical-soaked system. To go beyond it, and scale back the damage, we're going to need fermented foods, indoor fish races, synthetic juices/pulps/flours, proteins/meats, etc, etc. There's still a place for 'premium' food from local farms, etc. 'Cake' as you put it.
This is exactly wrong. I highly recommend you dig deeper, start with Wendell Berry and then into the authors and scientists in his orbit.