People wrote software before there’s was computers for them to grow up with. They’ll be able to develop these skills in university’s, colleges, coding courses or online.
I grew up prior to the app world. My exposure to computing during highschool was word, excel, access and once we used PowerPoint. Nothings changed, people are only taught what the teachers know.
It’s probably the same amount as before. More phones and tablets haven’t had a big effect on the amount of general purpose computers. There’s devices today like raspberry pi and Arduino that fill the same niche as older general-purpose computers.
Your assume things are different and must be worse. This is a take old as time. Socrates complained about the youth no longer taking the studies as serious as his generation did. The world would have fallen into complete chaos if it were ever true. It’s the conservative myth that things were better and can only get worse.
These kids accessing websites that tell you that a general purpose computer is needed, would have to rely on textbooks and magazines to get the same information in the past. A much bigger barrier, even identifying which ones you need.