Is that a fact? I'm sure plenty of people would once have said society will always need human "computers" (now so entirely replaced by machines that the original meaning of the word is a historical factoid). Or that society will always need assembly line workers (now well into the process of being replaced by robots).
When I check out at CVS I use a machine, not a human cashier. I bet there are restaurants in Japan/Korea with no human serving staff - just use the touch screen at the table to place your order and it pops out of a slot in the wall when it's ready. Cab drivers will be replaced by self-driving cars in the next 20 years. Et cetera. So I think that part of your comment is quite short-sighted.
On the other hand, the question of what all those folks will/should do once their economic value plummets (which, arguably, has already started happening) is a tricky one.
We as a society need to figure this out quickly. There's a video called Humans Need Not Apply that everyone should see: https://www.youtube.com/watch?v=7Pq-S557XQU
Of course it helps that educating in those fields isn't terribly expensive: you basically pay infrastructure and a few greybeards, the lower ranks are nearly working for free due to the low market value of their education and the resulting attractivity of maybe becoming one of the greybeards themselves. Also, some people might even understand that the greatest thinkers, just like the greatest sportsmen, are unlikely to be produced by focused training of a tiny elite selected by circumstances or a superficial entry test. Talent is rarely visible before a considerable amount of training has been applied.
Not saying it couldn't happen. Two scenarios I could see are everyone lives in a prefab home, when things start to go wrong you just replace it. That leaves all the plumbing to just cutting and bending pipes to pre-built designs and installing it in prearranged steps. I could see that being possible.
Another interesting case could be that all houses are 3d printed, with cavities for plumbing printed right into the fabric of the building, and possibly sealed in someway.
Currently we live in Microsoft houses, eventually we might live in Apple houses. That is a terrifying thought either way...
Even Mr Finch isn't that good at building AI's