That's like going back to 1971 and saying "there's no money in computers".
There'll always be niches, where people will make money creating bespoke software, but the kind of software that everyone uses will eventually be free, because once someone creates something free and sticks it on github, it doesn't get lost, it can only go in one direction - better.
Well, it could follow different directions, like "bloated", or like GNOME "better for us, but not for you", or "easier to maintain, but slower"