That was really the part I was most curious about. As the article points out, a lot of big tech has been trying to make their app economy "indispensable" to consumers, but competition seems to have thwarted that mostly. If Elon is saying he'll make it mandatory by other means, then I'm really curious to hear what he is saying on the subject.
What I hear from the marketing folks I work with is that these days it’s less about Google and more “if you’re not advertising on Facebook, you’re not advertising.” (US centric perspective.)
To answer your question, though, Visa doesn't process payments for the dozen or so cannabis shops in my town and they are all thriving. I'm not saying it's common, or easy, but the answer is yes.