“If it breaks, throwing it out and buying a new one is cheaper than getting it repaired” has been true of many physical items for decades already - that part isn’t even a future prediction. Doing that on the scale of a whole house is a leap, but if you want an example from the world of hammers and nails, how many people are paying the $100 call-out fee for a tradesperson to come and fix an issue with their $50 IKEA shelves?
I'm not sure what we are debating here. On one hand you said your prediction was fantastical but then you are trying to defend it? Plumbing and bookshelves are really different things. One has to be built in place and is completely custom, the other is a consumer item. You can draw parallels if you want but it doesn't make it a strong argument.
The original point was that becoming a plumber is a good way to ensure you won’t be made redundant by the march of technology. My belief is that “the trades are a pretty secure job” is true today in the same way that “being an $80/hr writer is a pretty secure job" was true yesterday.
There are differences between those situations (eg the trades being physical, hammer and nail, custom jobs), but those don't seem like particularly impassable obstacles to me, given that technology has already made redundant whole categories of physical, hammer and nail, custom jobs.
