Software development can be a high skilled job but entry level skills can be obtained in months, which is not coincidentally, how much training time seems to be involved with learning to be a long haul truck driver in the USA (I see quotes of about two months of full time study for the formal exam around the internet so maybe call that three months when employer training time is included). Three months of full time study isn't going to make you a well paid programmer but that's plenty of time to learn basic web development skills, and another two or three after that with a good course will get someone writing basic CRUD business web apps if they want to. Of course, it's the start of the journey, but now think how many clueless developers you've encountered who are earning good money.
Can the software development world absorb millions of new developers? Sure, it has done in the past, think dotcom boom. Trucking won't disappear over night, nor will taxi drivers, if only because of limited capacity to upgrade vehicle fleets even assuming the technology becomes perfect (which it isn't), and not all drivers will become software developers.